a, \(4\left(x-y\right)\left(x+y\right)-5\left(x+y\right)^2=\left(x+y\right)\left[4\left(x-y\right)-5\left(x+y\right)\right]\)
\(=\left(x+y\right)\left(4x-4y-5x-5y\right)=\left(x+y\right)\left(-x-9y\right)=-\left(x+y\right)\left(x+9y\right)\)
b, \(4\left(x+y\right)^2-6\left(x-y\right)\left(x+y\right)=2\left(x+y\right)\left[2\left(x+y\right)-3\left(x-y\right)\right]\)
\(=2\left(x+y\right)\left(2x+2y-3x+3y\right)=2\left(x+y\right)\left(5y-x\right)\)
a, 4(x−y)(x+y)−5(x+y)2
=(x+y)[4(x−y)−5(x+y)]4(x−y)(x+y)−5(x+y)2
=(x+y)[4(x−y)−5(x+y)]
=(x+y)(4x−4y−5x−5y)
=(x+y)(−x−9y)=−(x+y)(x+9y)
=(x+y)(4x−4y−5x−5y)=(x+y)(−x−9y)
=−(x+y)(x+9y)
b, 4(x+y)2−6(x−y)(x+y)
=2(x+y)[2(x+y)−3(x−y)]4(x+y)2−6(x−y)(x+y)
=2(x+y)[2(x+y)−3(x−y)]
=2(x+y)(2x+2y−3x+3y)
=2(x+y)(5y−x)
a) \(4\left(x-y\right)\left(x+y\right)-5\left(x+y\right)^2\)
\(=\left(x+y\right)\left(4x-4y-5x-5y\right)\)
\(=\left(x+y\right)\left(-x-9y\right)\)
b) \(4\left(x+y\right)^2-6\left(x-y\right)\left(x+y\right)\)
\(=2\left(x+y\right)\left(2x+2y-3x+3y\right)\)
\(=2\left(x+y\right)\left(5y-x\right)\)
