Toán Lớp 8: (x+1)^2-(x-1)^2+x(x^2+2)=(x+1)^3 Giúp em với ạ

Question

Toán Lớp 8:  (x+1)^2-(x-1)^2+x(x^2+2)=(x+1)^3  Giúp em với ạ

cobebongdem · Answer

#Sad   (x+1)^2-(x-1)^2+x(x^2+2) = (x+1)^3   &hArr; (x^2+2x+1)-(x^2-2x+1)+(x^3+2x) = x^3+3x^2+3x+1   &hArr; x^2+2x+1-x^2+2x-1+x^3+2x-x^3-3x^2-3x-1 = 0   &hArr; (x^3-x^3)+(x^2-x^2-3x^2)+(2x+2x+2x-3x)+(1-1-1) = 0   &hArr; -3x^2+3x-1 = 0   &hArr; -(3x^2-3x+1) = 0   &hArr; 3x^2-3x+1 = 0   &hArr; 3x^2-3x = -1   &hArr; 3x(x-1) = 1   &hArr; x-1 = 1/(3x)   &hArr; x = 1/(3x)+1  text{&rarr;V&ocirc; nghiệm}    text{Vậy kh&ocirc;ng c&oacute; nghiệm n&agrave;o thảo m&atilde;n phương tr&igrave;nh}

hiennhi98 · Answer

(x + 1)^2 - (x - 1)^2 + x(x^2 + 2) = (x + 1)^3   &hArr; (x^2 + 2x + 1) - (x^2 - 2x + 1) + (x^3 + 2x) = x^3 + 3x^2 + 3x + 1   &hArr; x^2 + 2x + 1 - x^2 + 2x - 1 + x^3 + 2x = x^3 + 3x^2 + 3x + 1   &hArr; 6x + x^3 = x^3 + 3x^2 + 3x + 1   &hArr; x^3 - x^3 + 3x^2 + 3x - 6x + 1 = 0   &hArr; 3x^2 - 3x + 1 = 0   &hArr; x^2 - x + 1/3 = 0   &hArr; x^2 - 2 . x . 1/2 + 1/4 - 1/4 + 1/3 = 0   &hArr; (x - 1/2)^2 + 1/12 = 0   text((V&ocirc; nghiệm))   text(Vậy kh&ocirc;ng c&oacute; x thỏa m&atilde;n phương tr&igrave;nh)