\(12x^2+7x-12\)

\(=12x^2-9x+16x-12\)

\(=3x\left(4x-3\right)+4\left(4x-3\right)\)

\(=\left(4x-3\right)\left(3x+4\right)\)

12x^2+7x-12=(12x^2-9x)+(16x-12)=3x(4x-3)+4(4x-3)=(3x+4)(4x-3)

chúc hok tốt

12x²+7x-12=-7

Đúng 100% 

Mình mới lớp 6 nhưng mình nghĩ thế này nha :

x(12x +7) -12

A=x^4+6x^3+7x^2–6x+1=x^4+(6x^3–2x^2)+(9x^2–6x+1)
= x^4+2x^2(3x–1)+(3x–1)^2 =(x^2+3x–1)^2

chỉnh lại tí

Đặt P(x)=x⁴+6x³+7x²- 6x+1

Đặt y=x²-1

=>y²=x⁴-2x²+1

P(x)=x⁴-2x²+1+6x³-6x+9x²

  =(x²-1)²+6x(x²-1)+9x²

Q(y)=y²+6xy+9x²

=(y+3x)²

P(x)=(x²-1+3x)²

a)\(\left(y-z\right)\left(12x^2-6x\right)+\left(y-z\right)\left(12x^2+6x\right)\)

\(=\left(y-z\right)\left(12x^2-6x+12x^2+6x\right)\)

\(=24x^2\cdot\left(y-z\right)\)

\(a,\left(y-z\right)\left(12x^2-6x\right)+\left(y-z\right)\left(12x^2+6x\right)\)
\(=\left(y-z\right)\left(12x^2-6x+12x^2+6x\right)\)
\(=24x^2\left(y-z\right)\)

\(6x^2-7x-20\)

\(=6x^2+8x-15x-20\)

\(=2x\cdot\left(3x+4\right)-5\left(3x+4\right)\)

\(=\left(3x+4\right)\left(2x-5\right)\)

\(6x^2-7x+1=6x^2-6x+1\)

\(\left(x-1\right)-\left(x-1\right)=\left(6x-1\right)\left(x-1\right)\)

\(12x^2+7x-12=12x^2-5x+12x-12\)

\(=x\left(12x-5\right)+12\left(x-1\right)\)

Đề sai rồi bạn ời

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

x⁴-6x³+12x²-14x+3 = (x² - 4x + 1) (x² - 2x + 3) 

\(7x-6x^2-2=-\left(6x^2-7x+2\right)\)

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

\(=-\left[3x\left(2x-1\right)-2\left(2x-1\right)\right]\)

\(=-\left(3x-2\right)\left(2x-1\right)\)

\(7x-6x^2-2\)

\(=-6x^2+7x-2\)

\(=\left(x-\frac{2}{3}\right)\left(x-\frac{1}{2}\right)\)