Question

a)5x²-20x+20-5y²

b)(x-y+5)²-2(x-y+5)+1

c)7x-7y+5x-5y

d)16x²-8x+1

e)100x²-(x²+25)²

^{chỉ dùm e vs em cần gấp}

Answer 1

a) \(5x^2-20x+20y-5y^2\)

\(=5\left(x^2-y^2\right)-20\left(x-y\right)\)

\(=5\left(x-y\right)\left(x+y\right)-20\left(x-y\right)\)

\(=5\left(x-y\right)\left(x+y-4\right)\)

b) \(\left(x-y+5\right)^2-2\left(x-y+5\right)+1\)

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

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

c) \(7x-7y+5x-5y\)

\(=7\left(x-y\right)+5\left(x-y\right)\)

\(=\left(x-y\right)\left(7+5\right)\)

\(=12\left(x-y\right)\)

d) \(16x^2-8x+1\)

\(=\left(4x\right)^2-2.4x+1\)

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

e) \(100x^2-\left(x^2+25\right)^2\)

\(=\left(10x\right)^2-\left(x^2+25\right)^2\)

\(=\left(10x-x^2+25\right)\left(10x+x^2+25\right)\)

\(=\left(10x-x^2+25\right)\left(x+5\right)^2\)