(3x + 2)2 - 4 = ( 3x + 2 )2 - 22
= ( 3x + 2 - 2)(3x + 2+2) = 3x(3x + 4)
= 9x2 + 12x
(3x + 2)2 - 4
=>(3x+2-2)(3x+2+2)
=>3x(3x+4)
Chúc lm tốt @!
\(\left(3x+2\right)^2-4=\left(3x+2-2\right)\left(3x+2+2\right)\) \(=3x\left(3x+4\right)\)
Cách 1:
Ta có:
= \(\left(3x+2\right)^2-2^2\)
= \(\left(3x+2-2\right).\left(3x+2+2\right)\)
= \(3x.\left(3x+4\right)\)
Cách 2:
Ta có: (3x + 2)2 - 4
= \(\left(9x^2+12x+4\right)-4\)
= \(9x^2+12x+4-4\)
= \(9x^2+12x\)
= \(3x.\left(3x+4\right)\)
