Răspuns:
Se folosesc formulele acestea:
(a+b)^2=a^2+2ab+b^2
a^3+b^3=(a+b)(a^2+ab+b^2)
a^2-b^2=(a+b)(a-b)
a^3+a^2b+3ab^2+b^3=(a+b)^3
a^2+b^2+c^2+2ab+2ac+2bc=(a+b+c)^2
Explicație pas cu pas:
a)(3x+4y)²=9x²+3x·2·4y+16y²=9x²+24xy+16y
b)(2x-5y)²=4x-20xy+25y²
c)x²-16=(x-4)(x+4)
d)13x-13y=13(x-y)
e)9ax-11ay+2az-5at=a(9x-11y+2z-5t)
f)9x²+12x+4=(3x+2)²
g)4x²-49=(2x-7)(2x-7)
h)4x²-20x+25=(2x-5)²
I)2x+2y+2z=2(x+y+z)
j)3x(x-2)-5(x-2)²=3x²-6x-5(x²-4x+4)=3x²-6x-5x²+20x+20=-2x²+14x+20
