Question

Utilizand formulele de calcul prescurtat efectuati:
a) (x+1)(x-1)=
b) (a-3)(a+3)=
c) (2x-1)(2x+1)=
d) (2y-3x)(2y+3x)=
e) (2x-3)^2=
f) (3x+5y)^2=
g) (11x+3)^2=
h) (3x+4y)(3x-4y)=

Answer 1

$a).(x+1)(x-1)=x^2-1 \\ b).(a-3)(a+3)=a^2-9 \\ c).(2x-1)(2x+1)=4x^2-1 \\ d).(2y-3x)(2y+3x)=4y^2-9x^2 \\ e).(2x-3)^2=(2x)^2-2*2x*3+3^2=4x^2-12x+9 \\ f).(3x+5y)^2=(3x)^2+2*3x*5y+(5y)^2=9x^2+30xy+25y^2 \\ g).(11x+3)^2=(11x)^2+2*11x*3+3^2=121x^2+66x+9 \\ h).(3x+4y)(3x-4y)=9x^2-16y^2$