Toán Lớp 8: a)x(x-1)-(x-2) ²=5 b)x(4x-1)-(2x+1) ²=2 Nhanhh ạ

Question

Toán Lớp 8:  a)x(x-1)-(x-2) ²=5  b)x(4x-1)-(2x+1) ²=2 Nhanhh ạ

maingoctruc · Answer

Giải đáp:    $a) x.(x-1)-(x-2)&sup2;=5$   $&hArr; x&sup2;-x-(x&sup2;-4x+4)=5$   $&hArr; x&sup2;-x-x&sup2;+4x-4=5$   $&hArr; (x&sup2;-x&sup2;)+(4x-x)-4=5$   $&hArr; 3x-4=5$   $&hArr; 3x=9$   $&hArr;x=3$   $Vậy$ $x=3$   $b) x.(4x-1)-(2x+1)&sup2;=2$   $&hArr; 4x&sup2;-x-(4x&sup2;+4x+1)=2$   $&hArr; 4x&sup2;-x-4x&sup2;-4x-1=2$   $&hArr; (4x&sup2;-4x&sup2;)-(x+4x)-1=2$   $&hArr; -5x-1=2$   $&hArr; -5x= 3$   $&hArr; x= dfrac{-3}{5}$   $Vậy$ $x= dfrac{-3}{5}$

thienthanh · Answer

Giải đáp + Lời giải và giải thích chi tiết :       a) x ( x - 1 ) - ( x - 2 )^2 = 5     &hArr; x^2 - x - ( x^2 - 4x + 4 ) = 5     &hArr; x^2 - x - x^2 + 4x - 4 = 5     &hArr; 3x - 4 = 5     &hArr; 3x = 9     &hArr; x = 3     Vậy x = 3     b) x ( 4x - 1 ) - ( 2x + 1 )^2 = 2     &hArr; 4x^2 - x - ( 4x^2 + 4x + 1 ) = 2     &hArr; 4x^2 - x - 4x^2 - 4x - 1 = 2     &hArr; - 5x - 1 = 2     &hArr; - 5x = 3     &hArr; x = - 5/3     Vậy x = - 5/3     $# Mon $ $# Xin Hay Nhất $