giúp toi

\(6x^2-12x-7x+14\)

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

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

6x²-7x-20

= 6x²-15x+8x-20

= 3x(2x-5) + 4(2x-5)

= ( 2x-5 )(3x+4)

<=> x= 5/2 hoặc x= -4/3 

Vậy .........

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

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

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

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

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

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

\(=7x\left(1-x\right)+y\left(1-x\right)\\ =\left(7x+y\right)\left(1-x\right)\)

\(7x+y-7x^2-xy=7x\left(1-x\right)+y\left(1-x\right)=\left(7x+y\right)\left(1-x\right)\)

\(x^2-7x-8\\=x^2+x-8x-8\\=x(x+1)-8(x+1)\\=(x+1)(x-8)\)

sửa đề xíu:

\(2x^2+7x+5=2x^2+2x+5x+5=\left(2x^2+2x\right)+\left(5x+5\right)=2x\left(x+1\right)+5\left(x+1\right)=\left(x+1\right)\left(2x+5\right)\)

`2^2` à bạn?

7 x - 6 x 2 - 2 = 4 x - 6 x 2 - 2 + 3 x = 4 x - 6 x 2 - 2 - 3 x = 2 x 2 - 3 x - 2 - 3 x = 2 x - 1 2 - 3 x

\(a,4x^2-y^2-1-4x\)

\(\Rightarrow\left(4x^2+4x+1\right)-y^2\)

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

\(b,6x^2-7x-20=6x^2-15x+8x-20\)

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

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

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

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

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

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

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

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

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