Bài 1 :
a)3x+6y
=3(x+y)
b)\(x^2-y^2-7x+7y\)
\(=\left(x-y\right)\left(x+y\right)-7\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y-7\right)\)
câu c sai đề à
d)\(4x^2-4x-15\)
\(=\left(4x^2-4x+1\right)-16\)
\(=\left(2x-1\right)^2-16\)
\(=\left(2x-1-4\right)\left(2x-1+4\right)\)
\(=\left(2x-5\right)\left(2x+3\right)\)
a)3x+6y = 3( x + 2y )
b)
= 3b - ( x\(^2\) - 4xy + 4y\(^2\)) = 3b - ( x - 2y )\(^2\) câu này hình như sai chỗ 3b phải ko
d) = 4x\(^2\) - 10x + 6x -15 =0
= 2x ( 2x +3 ) - 5 ( 2x + 3 ) = 0
= ( 2x - 5 )( 2x + 3)
4x2−4x−15