Question

Me ajudem ai

calcule
a) (5x-1) . (5x+1)
b) (a+b) . (a+b)
c) ( 2x²-3x-6) . (5x-2)
d) (2a+3 b ) . ( a-1 b)
5 2

Answer 1

a) $(5x-1)(5x+1)=(5x)^2-1^2=25x^2-1$

b) $(a+b)(a+b)=a^2+ab+ba+b^2=a^2+2ab+b^2$

c) $(2x^2-3x-6)(5x-2)=10x^3-15x^2-30x-4x^2+6x+12$

$(2x^2-3x-6)(5x-2)=10x^3-19x^2-24x+12$

d) $\left(\dfrac{2a+3b}{5}\right)\left(\dfrac{a-b}{2}\right)=\dfrac{2a^2}{10}-\dfrac{2ab}{10}+\dfrac{3ab}{10}-\dfrac{3b^2}{10}=\dfrac{a^2}{5}+\dfrac{ab}{10}-\dfrac{3b^2}{10}$