\(a^2-4b^2\)

= \(\left(a-2b\right)\left(a+2b\right)\)

\(a^2-4b^2=a^2-\left(2b\right)^2=\left(a-2b\right)\left(a+2b\right)\)

a) \(a^2-4b^2\)

= \(\left(a-4b\right).\left(a+4b\right)\)

= \(a^2\)

\(3x^2-3y^2-2\left(x-y\right)^2\)

\(=3x^2-3y^2-2\left(x^2-2xy+y^2\right)\)

\(=3x^2-3y^2-2x^2+4xy-2y^2\)

\(=x^2+4xy-5y^2\)

\(=x^2+4xy+4y^2-9y^2\)

\(=\left(x+2y\right)^2-\left(3y\right)^2\)

\(=\left(x+2y-3y\right)\left(x+2y+3y\right)\)

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

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

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

3x^2-3x-6

=3(x^2-x-2)

=3(x-2)(x+1)

a) x³-2x²-x+2

=x(x²-1)+2(-x²+1)

=x(x²-1)-2(x²-1)

=(x²-1)(x-2)

b)

x²+6x-y²+9

=x²+6x+9-y²

=(x+3)²-y²

^{=(x+3-y)(x+3+y)}

d: \(9x^2-25=\left(3x-5\right)\left(3x+5\right)\)

e: \(16x^2-4y^2=4\left(4x^2-y^2\right)=4\left(2x-y\right)\left(2x+y\right)\)

f: \(\left(x+\dfrac{1}{4}\right)^2=x^2+\dfrac{1}{2}x+\dfrac{1}{16}\)

\(d,9x^2-25=\left(3x-5\right)\left(3x+5\right)\\ e,16x^2-4y^2=\left(4x-2y\right)\left(4x+2y\right)=4\left(2x-y\right)\left(2x+y\right)\)

d: \(9x^2-25=\left(3x-5\right)\left(3x+5\right)\)

e: \(16x^2-4y^2=4\left(4x^2-y^2\right)=4\left(2x-y\right)\left(2x+y\right)\)

đề là gì?

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

x²+5x+4

(x²+5x)+4

x(x+5)+4