Câu hỏi của Lê Nguyên Anh Tài

Question

Phân tích đa thức sau thành nhân tử:

a) x^2-7x-30

b) x^2-x-6

c) x^2+x-30

Huy Thắng Nguyễn · Accepted Answer

a) $x^2-7x-30$

$=x^2+10x-3x-30$

$=x\left(x+10\right)-3\left(x+10\right)$

$=\left(x+10\right)\left(x-3\right)$

b) $x^2-x-6$

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

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

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

c) $x^2+x-30$

$=x^2+6x-5x-30$

$=x\left(x+6\right)-5\left(x+6\right)$

$=\left(x+6\right)\left(x-5\right)$Câu trả lời: a) $x^2-7x-30$

$=x^2+10x-3x-30$

$=x\left(x+10\right)-3\left(x+10\right)$

$=\left(x+10\right)\left(x-3\right)$

b) $x^2-x-6$

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

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

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

c) $x^2+x-30$

$=x^2+6x-5x-30$

$=x\left(x+6\right)-5\left(x+6\right)$

$=\left(x+6\right)\left(x-5\right)$

T.Thùy Ninh · Answer

$a,x^2-7x-30=x^2-10x+3x-30$

$=x\left(x-10\right)+3\left(x-10\right)$

$=\left(x-10\right)\left(x+3\right)$

$b,x^2-x-6=x^2-3x+2x-6$

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

$c,x^2+x-30=x^2-5x+6x-30$

$=x\left(x-5\right)+6\left(x-5\right)=\left(x+6\right)\left(x-5\right)$Câu trả lời: $a,x^2-7x-30=x^2-10x+3x-30$

$=x\left(x-10\right)+3\left(x-10\right)$

$=\left(x-10\right)\left(x+3\right)$

$b,x^2-x-6=x^2-3x+2x-6$

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

$c,x^2+x-30=x^2-5x+6x-30$

$=x\left(x-5\right)+6\left(x-5\right)=\left(x+6\right)\left(x-5\right)$

Bài 9: Phân tích đa thức thành nhân tử bằng cách phối hợp nhiều phương pháp