Question

Calculati: a) (x+3y)²+(x-3y)(x+3y)=
b) (4x-3)²+5x(x-3)=
c) (1+x)²+(2+x)²+(3+x)²=
d) (x²+y)²-(x²-y)²=
Va multumesc!

Answer 1

a) (x+3y)² + (x-3y)(x+3y)=(x+3y)((x+3y+x-3y)=(x+3y)(2x)=2x²+6xy ;
b)  ...=16x²-24x+9 + 5x²-15 = 21x²-24x-6 ;
c)  ...=1+2x+x² + 4+4x+x² + 9+6x+x² = 3x²+12x+14 ;
d)  ...=x²+y² - x²+y² = 2y² ;