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A melhor resposta!
2014-07-24T17:45:36-03:00
Olá, Stefani001!

(x-5)²
x² + 2.x.5 + 5²
x² + 10x + 25

(2a+9)²
(2a)² + 2.2a.9 + 9²
4a² + 36a + 81

(4x - 3y)(4x+3y)
16x² + 12xy - 12xy - 9y²
16x² - 9y²


2 5 2
2014-07-24T17:48:39-03:00
(x-5) (x-5)= x²-5x-5x+25=0     x²-10x+25=0
(2a+9) (2a+9)= 4a²+18a+18a+81=0   4a²+36a+81=0
(4x-3y) (4x+3y)= 16x²+12xy-12xy-9y=0     16x²+9y=0