Câu hỏi của HOANG HA

Question

phan tich da thuc thanh nhan tu :

a,(x-5)^2+(x-5)(x+5)-(5-x)(2x+1)

b,$\left(3x-2\right)\left(4x-3\right)-\left(2-3x\right)\left(x-1\right)-2\left(3x-2\right)\left(x+1\right)$

DƯƠNG PHAN KHÁNH DƯƠNG · Accepted Answer

Câu a :

$\left(x-5\right)^2+\left(x-5\right)\left(x+5\right)-\left(5-x\right)\left(2x+1\right)$

$=x^2-10x+25+x^2-25-10x-5+2x^2+x$

$=4x^2-19x-5$

Câu b :

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

$=12x^2-9x-8x+6-2x+2+3x^2-3x-6x^2-6x+4x+4$