Câu hỏi của vô danh

Question

tìm x,biết:

a,(x+8).(x+2)-x^2=104

b,(x+1).(x+2)-(x-3).(x+4)=6

Nguyễn Việt Lâm · Accepted Answer

a.

$\left(x+8\right)\left(x+2\right)-x^2=104$

$x^2+2x+8x+16-x^2=104$

$10x+16=104$

$10x=104-16$

$10x=88$

$x=88:10$

$x=8,8$

b.

$\left(x+1\right)\left(x+2\right)-\left(x-3\right)\left(x+4\right)=6$

$\left(x^2+2x+x+2\right)-\left(x^2+4x-3x-12\right)=6$

$x^2+3x+2-\left(x^2+x-12\right)=6$

$x^2+3x+2-x^2-x+12=6$

$2x+14=6$

$2x=6-14$

$2x=-8$

$x=-4$

Câu trả lời:

a.