Giải tích 12- Chương III Nguyên hàm - tích phân và ứng dụng
1 Tính diện tích hình phẳng giới hạn bởi các đường sau :
a. Y= 2x –x2 ,x + y = 2
b. Y = x3 – 12x , y = x2
c. X + y = 1 ,x+y = - 1 , x – y =1. x – y = -1
d. y= x3 – 1 và tiếp tuyến với y = x3 – 1taij điểm ( -1, -2)
............. ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 6. Tìm nguyên hàm của hàm số sau : a. y = 1 - x b. y = 2 + x2 c. y = x3 – 9 d. y = 25+ 13ex e. y = 122- 1x2 f. y = 52 x32+8x Giải ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... 7. Tìm nguyên hàm của hàm số sau : a. y = (x + 2)(x - 3 ) b. y = (x2 - 3x) c. y = (x – 3)2 d.y = (x + 2x3)(x + 1) Giải ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... 8. Tìm : a. x2-3xxdx b. 4x3+5x2-1x2dx c. (x+2)2x4dx d. (x+1)2x2dx Giải ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... . 9. Tìm: a. x34+x12-5dx b. xx-2xx+1dx c. x-3-2x-2+4x+1dx d. (2x+3x-2)x2-1x+3x-3dx Giải ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... . ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... PHẦN TRẮC NGHIỆM 1.Hàm số F(x)=x+1x là một nguyên hàm của hàm số nào sau đây: (A) f(x)=x2+1x2 (B) f(x)=1x2 (C) f(x)= 1x2 + x (D) f(x)=x2-1x2 2. Nguyên hàm của f(x)=(2x+1)3 là: (A) F(x)=(2x+1)44+C (B) f(x)=2(2x+1)3 +C (C) F(x)=(x+1)42+C (D) f(x)= (x+1)48+C 3. Một nguyên hàm của hàm số f(x)=4cos2x là: (A) 4xsin2x (B) 4 + tanx (C) tanx (D) 4x+43 tan3x 4. Một nguyên hàm F(x)của f(x)= 4 cos2x là: (A) x2 – 1 (B) x3+ x – 2 (C)x3 – 4 (D)2x3 – 2 5. Một nguyên hàm của hàm số : f(x)= x-1(x+1)x4 là : (A) 1 3x3- 1x (B) x3- 1x4 (C) 1x- 13x3 (D) x2- 13x3 6. Môt nguyên hàm của f(x)= cosx 3x cos2x bằng : (A) 12sinx+12sinx5x (B) 12sinx+110sinx5x (C) 12cosx+110sinx5x (D) Một hàm số khác 7.Nguyên hàm của f(x)= 1x2 triệt tiêu khi x=1 lf hàm số nào ? (A) 1-xx (B)12x- 12 (C)3x3-3 (D)x-1x 8. Nguyên hàm của f(x)= 22x triệt tiêu khi x=1 lf hàm số nào ? (A) F(x)= 2x+C (B) F(x)= -2x+C (C) F(x)= 22x+C (D) F(x)= 12x +C 9. Cho hàm số f(x)=sin2xcos2x và các hàm số : I /.14sin2x II/ 14cos22x III/ - 18cos4x Hàm số nào là một số nguyên của hàm số f(x) ? Chỉ I (B) Chỉ II Chỉ I và II (D) Chỉ I và III 10. Tinh 3xdx kết quả là: (A) 34x43 +C (B) 34x3 +C (C)343x2 + C (D) 34xx +C 11.Tính xdxx2+1 kết quả là: (A) 2x+C (B) 12 ln(x2 + 1) + C (C) ln(x2 + 1) + C (D)1 2 lnx-1x+1 + C 12. Tính tan3xdx kết quả là: (A) tan2x2 + x + C (B) tan2x2 - x + C (C) lncos3x +C (D)12cos2x + lncosx +C 13. Tính xcosxdx kết quả là: (A) – x22sinx +C (B) xsinx+cosx + C (C) cosx – sinx + C (D) xsinx – cosx + C 14. Tính excosxdx kết quả là : (A) ex2 (sinx + cosx) + C (B) e3 sinx + C (C) - e3 sinx + C (D) (sinx + cosx) + C Bài 2: MỘT SỐ PHƯƠNG PHÁP TÍNH NGUYÊN HÀM I .TÍNH NGUYÊN HÀM BẰNG PHƯƠNG PHÁP ĐỔI BIẾN : 1Dạng 1: TimfI=fuxu'x.dx→Đặt t=ux→dt=u'x.dx →I=ftdt=Ft+ C=F[u(x)]+C 2.Dạng 2: I=fx.dx1→Đặtx=φu=>dx=φ'udu.Thay vào 1=>kq? 6 DẠNG ĐỔI BIẾN CƠ BẢN Dạng 1: I=eu(x)dx→đặt t = u(x) (đặt t =mũ ).Dùng công thức: I=et.dt= et+C Dang 2: I = u'xu(x) .dx→đăt t=uxđặt t=mẫu . Dùng công thức: I=dtt=lnt+C Dạng 3: Inu(x).u’(x)dx →đặt t=uxđặt t=căn.Dùng công thức: I=tα.dt=tα+1α+1+C Dạng 4: I = sinnx.cosmx.dx→đặt t=ux, dựa vào bản sau để chọn cách đặt t cho phù hợp Chẳn Lẽ Chẵn Không đặt t mà dùng công thức hạ bậc Đặt t = sinx Lẽ Đặt t = sinx Đặt t = hslg có mũ nhỏ Dạng 5: I=dxa2+x2→đặt x=a.tant=>dx=(1 + tan2t)dt =>I=a1+tan2tdta2+a2tan2t=a1+tan2ta2(1+tan2t)dt= 1adt=1at+C Dạng 6: I = dxa2-x2 → đặt x=a.sint =>dx=a.cost.dt =>I = a.costdta2-a2sin2t = a.costa.costdt=dt=t+C BÀI TẬP TRONG SÁCH GIÁO KHOA 1.[3/101-CB] Sử dụng phương pháp ssooir biến số, hảy tính: a. (1-x)2dx (đặt u=1-x) b.x(1+x2)32dx (đặt u=(1+x2) c. cos3x.sinxdx đặt t=cosx d. 1ex+e-x+2dx (đặt u=ex+1) Giải: ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ ........................................................................................................................ 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........................................................................................................................ ....................................................................................................................... ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... . ........................................................................................................................ 2 .[4/101-CB] Sử dụng phương pháp tính nguyên hàm từng phần , hảy tính : a.xln1+xdx b(x2+2x-1)exdx c.xsin2x+1dx d.1-xcosxdx Giải: ........................................................................................................................ 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........................................................................................................................ ........................................................................................................................ ....................................................................................................................... . 3.[5/145-CB] Dùng phương pháp đổi biến số, tìm nguyên hàm của các hàm số sau : a. f(x)=9x21-x3 (HD:Đặt u= 1 - x3) b. f(x)= 15x+4 (HD:Đặt u= 5x+4) c.f(x)= x41-x2 (HD:Đặt u= 1 – x2) d.f(x)= 1x(1+x)2 (HD:Đặt u= 1 + x) Giải: ........................................................................................................................ ........................................................................................................................ ....................................................................................................................... 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