Đáp án:
$a) (1-3x)(1+3x)\\
b)
(4x-0,1)(4x+0,1)\\
c)
\left ( \dfrac{x}{3}-\dfrac{y}{4} \right )\left ( \dfrac{x}{3}+\dfrac{y}{4} \right )\\
d)
(a^2-b^2)(a^2+b^2)\\
e)
(a-b+1)(a-b-1)\\
g)(2-a+b)(2+a-b)\\
h)
(x-y+m+n)(x-y-m-n)\\
i)
(x+y)(5x-5y)$
Giải thích các bước giải:
$a) 1-9x^2=1-(3x)^2=(1-3x)(1+3x)\\
b)
16x^2-0,01=(4x)^2-0,1^2=(4x-0,1)(4x+0,1)\\
c)
\dfrac{x^2}{9}-\dfrac{y^2}{16}=\left ( \dfrac{x}{3} \right )^2-\left ( \dfrac{y}{4} \right )^2=\left ( \dfrac{x}{3}-\dfrac{y}{4} \right )\left ( \dfrac{x}{3}+\dfrac{y}{4} \right )\\
d)
a^4-b^4=(a^2)^2-(b^2)^2=(a^2-b^2)(a^2+b^2)\\
e)
(a-b)^2-1=(a-b+1)(a-b-1)\\
g)4-(a-b)^2=2^2-(a-b)^2=(2-a+b)(2+a-b)\\
h)
(x-y)^2-(m+n)^2=(x-y+m+n)(x-y-m-n)\\
i)
(3x-2y)^2-(2x-3y)^2=(3x-2y-2x+3y)(3x-2y+2x-3y)=(x+y)(5x-5y)$
