Question

Answer 1

Bài 3:

e: \(x^2+2xy+y^2=\left(x+y\right)^2\)

f: \(a^2-2ab+b^2=\left(a-b\right)^2\)

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

h: \(1-6x+9x^2=1^2-2\cdot1\cdot3x+\left(3x\right)^2=\left(1-3x\right)^2\)

Bài 4:

a: \(\left(x+2\right)^2-x\left(x-6\right)\)

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

=10x+4

b: \(\left(x-1\right)^2-\left(x-3\right)\left(x-2\right)\)

\(=x^2-2x+1-\left(x^2-5x+6\right)\)

\(=x^2-2x+1-x^2+5x-6=3x-5\)

c: \(\left(a-b\right)^2+a\left(a+2b\right)\)

\(=a^2-2ab+b^2+a^2+2ab\)

\(=2a^2+b^2\)

d: \(\left(a+2b\right)^2-3b\left(a+b\right)\)

\(=a^2+4ab+4b^2-3ab-3b^2\)

\(=a^2+ab+b^2\)