Question

Daca x-y -3 si x²-y²=12,determinati numarul: a=(x+y)+(x+y)²+(x+y)³"

Answer 1

nu pare complicat doar ca x-y=3 sau x-y-3=12?

x-y=3=>x=3+y
x^2-y^2=12=>(3+y)^2-y^2=12
9+6y+y^2-y^2=12
6y=3
y=1/2
x=3+1/2=7/2

x+y=1/2+7/2=8/2=4
a=4+4^2+4^3

Answer 2

$x^2-y^2=12 \Longleftrightarrow (x-y)(x+y)=12 \Rightarrow x+y=4.$
Asadar $a=(x+y)+(x+y)^2+(x+y)^3=4+4^2+4^3=4(1+4+4^2)=84.$