Toán Lớp 8: thực hiện phép chia a,[15.(x-y)^3+12.(y-x)^2-x+y]:(3y-3x) b,[5.(x-2y)^4+(x-2y)^2+2y-x]:(x-2y) c,[6.(x+y)^3-5.(x+y)^2+3.(x+y)]:(x+y) d,(

Question

Toán Lớp 8:  thực hiện phép chia a,[15.(x-y)^3+12.(y-x)^2-x+y]:(3y-3x) b,[5.(x-2y)^4+(x-2y)^2+2y-x]:(x-2y) c,[6.(x+y)^3-5.(x+y)^2+3.(x+y)]:(x+y) d,(5x^2-3x^3+15-9x):(5-3x) e,(-x^2+6x^3-26x+21):(3-2x) g,(x^2+x^3-1+5x):(x-1) i,(2x^4+2x^3+3x^2-5x-2x):(x^2+x+4)

annhocbichchaubich · Answer

Hướng dẫn trả lời:     a) [15cdot(x - y)^3 + 12cdot(y - x)^2 - x + y] &divide; (3y - 3x)   = [15cdot(x - y)^3 + 12cdot(x - y)^2 - (x - y)] &divide; (- 3x + 3y)   = (x - y)cdot[15cdot(x - y)^2 + 12cdot(x - y) - 1] &divide; - 3cdot(x - y)   = (x - y)cdot[(-3)cdot(-5)cdot(x - y)^2 + (-3)cdot(-4)cdot(x - y) - 3cdot1/3] &divide; - 3cdot(x - y)   = - 3cdot(x - y)cdot[-5cdot(x - y)^2 - 4cdot(x - y) + 1/3] &divide; - 3cdot(x - y)   = -5cdot(x - y)^2 - 4cdot(x - y) + 1/3   b) [5cdot(x - 2y)^4 + (x - 2y)^2 + 2y - x] &divide; (x - 2y)   = [5cdot(x - 2y)^4 + (x - 2y)^2 - (x - 2y)] &divide; (x - 2y)   = (x - 2y)cdot[5cdot(x - 2y)^3 + (x - 2y) - 1] &divide; (x - 2y)   = 5cdot(x - 2y)^3 + (x - 2y) - 1   c) [6cdot(x + y)^3 - 5cdot(x + y)^2 + 3cdot(x + y)] &divide; (x + y)   = [(x + y)cdot6cdot(x + y)^2 - (x + y)cdot5cdot(x + y) + (x + y)cdot3] &divide; (x + y)   = (x + y)cdot[6cdot(x + y)^2 - 5cdot(x + y) + 3] &divide; (x + y)   = 6cdot(x + y)^2 - 5cdot(x + y) + 3   d) (5x^2 - 3x^3 + 15 - 9x) &divide; (5 - 3x)   = [(5x^2 - 3x^3) + (15 - 9x)] &divide; (5 - 3x)   = [x^2cdot(5 - 3x) + 3cdot(5 - 3x)] &divide; (5 - 3x)   = (x^2 + 3)cdot(5 - 3x) &divide; (5 - 3x)   = x^2 + 3   e) (-x^2 + 6x^3 - 26x + 21) &divide; (3 - 2x)   = (6x^3 - x^2 - 26x + 21) &divide; (- 2x + 3)   = [(6x^3 + 8x^2 - 14x) + (- 9x^2 - 12x + 21)] &divide; (- 2x + 3)   = [- 2xcdot(-3x^2 - 4x + 7) + 3cdot(-3x^2 - 4x + 7)] &divide; - (2x - 3)   = (- 2x + 3)cdot(-3x^2 - 4x + 7) &divide; - (2x - 3)   = - (2x - 3)cdot(-3x^2 - 4x + 7) &divide; - (2x - 3)   = -3x^2 - 4x + 7   g) (x^2 + x^3 - 1 + 5x) &divide; (x - 1)   Sửa đề: (x^3 - x^2 + x^5 - 1) &divide; (x - 1)   = [(x^5 + x^3) - (x^2 + 1)] &divide; (x - 1)   = [x^3cdot(x^2 + 1) - 1cdot(x^2 + 1)] &divide; (x - 1)   = (x^3 - 1)cdot(x^2 + 1) &divide; (x - 1)   = (x^3 - 1^3)cdot(x^2 + 1) &divide; (x - 1)   = (x - 1)cdot(x^2 + xcdot1 + 1^2)cdot(x^2 + 1) &divide; (x - 1)   = (x - 1)cdot(x^2 + x + 1)cdot(x^2 + 1) &divide; (x - 1)   = (x^2 + x + 1)cdot(x^2 + 1)   i) Đề sai, m&igrave;nh sẽ sửa nh&eacute;!   (2x^4 + 2x^3 + 3x^2 - 5x - 2x) &divide; (2x^2 + 4x + 7)   = (2x^4 + 2x^3 + 3x^2 - 7x) &divide; (2x^2 + 4x + 7)   = xcdot(2x^3 + 2x^2 + 3x - 7) &divide; (2x^2 + 4x + 7)   = xcdot(2x^3 + 4x^2 - 2x^2 + 7x - 4x - 7) &divide; (2x^2 + 4x + 7)   = xcdot[(2x^3 + 4x^2 + 7x) - (2x^2 + 4x + 7)] &divide; (2x^2 + 4x + 7)   = xcdot[xcdot(2x^2 + 4x + 7) - 1cdot(2x^2 + 4x + 7)] &divide; (2x^2 + 4x + 7)   = xcdot(x - 1)cdot(2x^2 + 4x + 7) &divide; (2x^2 + 4x + 7)   = xcdot(x - 1)