Câu hỏi của Linh

Question

tìm x biết

a) x ( 5 - 2x ) + 2x ( x - 1 ) =13

b ) 9x ( x - 1 ) - (3x - 1 ) ^ 2 =11

Phạm Thị Trâm Anh · Accepted Answer

a) $x.\left(5-2x\right)+2x.\left(x-1\right)=13$

$\Rightarrow5x-2x^2+2x^2-2x=13$

$\Rightarrow3x=13$

$\Rightarrow x=\dfrac{13}{3}$

b) $9x.\left(x-1\right)-\left(3x-1\right)^2=11$

$\Rightarrow9x^2-9x-\left(9x^2-6x+1\right)=11$

$\Rightarrow3x=12$

$\Rightarrow x=4$Câu trả lời: a) $x.\left(5-2x\right)+2x.\left(x-1\right)=13$

$\Rightarrow5x-2x^2+2x^2-2x=13$

$\Rightarrow3x=13$

$\Rightarrow x=\dfrac{13}{3}$

b) $9x.\left(x-1\right)-\left(3x-1\right)^2=11$

$\Rightarrow9x^2-9x-\left(9x^2-6x+1\right)=11$

$\Rightarrow3x=12$

$\Rightarrow x=4$

Trần Thị Tuyết Ngân · Answer

a) x ( 5 - 2x) + 2x (x - 1 ) = 13

$\Rightarrow$ 5x - 2x2 + 2x3 - 2x =  13

( 5x - 2x ) + (-2x2 + 2x3) = 13

3x + x =13

4x = 13

x = $\dfrac{13}{4}$

b) 9x ( x - 1 ) - ( 3x - 1 )2 = 11

$\Rightarrow$ 9x2 - 9x - ( 9x2 - 6x + 1 ) = 11

3x = 12

x = 12/3 = 4Câu trả lời: a) x ( 5 - 2x) + 2x (x - 1 ) = 13