Respuestas

2011-12-27T17:58:15+01:00

a)

(2a-6)^2 =(2a)^2 - 2 *2a*6 + 6^2 =  4a^2 - 24a + 36

b)

(1/2 a-4b)^2 = (1/2 a)^2 - 2*1/2 a*4b + (4b)^2 = 1/4 a^2 - 4ab + 16b^2

c)

(x-y)(x+y) = x^2 - y^2

d)

(4+V5 z)(4-V5 z) = 16 - 5z^2