\(\left(1+2x\right)\left(1-2x\right)-\left(x-2\right)\left(x+2\right)\)
\(=\left(1-4x^2\right)-\left(x^2-4\right)\)
\(=1-4x^2-x^2+4\)
\(=5-5x^2=5\left(1-x^2\right)\)
\(=5\left(1-x\right)\left(1+x\right)\)
\(x^2+7x+12\)
\(=\left(x^2+7x+12,25\right)-0,25\)
\(=\left(x+3,5\right)^2-0,25\)
\(=\left(x+3,5\right)^2-\left(0,5\right)^2\)
\(=\left(x+3,5-0,25\right)\left(x+3,5+0,25\right)\)
\(=\left(x+3,25\right)\left(x+3,75\right)\)
Sai đề rồi, mình sửa lại:
\(3x^2-3xy-5x+5y\)
\(=3x\left(x-y\right)-5\left(x-y\right)=\left(3x-5\right)\left(x-y\right)\)
(1 + 2x)(1 - 2x) - (x + 2)(x - 2)
= (1 - 4x2) - (x2 - 4)
= 1 - 4x2 - x2 + 4
= 5 - 5x2
= 5(1 - x2)
x2 + 7x + 12
= x2 + 3x + 4x + 12
= (x2 + 3x) + (4x + 12)
= x(x + 3) + 4(x + 3)
= (x + 4)(x + 3)
3x2 - 3xy - 5x + 5y
= (3x2 - 3xy) - (5x - 5y)
= 3x(x - y) - 5(x - y)
= (3x - 5)(x - y)
