Question

Daca x-y=3 si x la puterea a2 -y la puterea a2 =12 Determinati numarul a=(x-y)+(x+y)la puterea a 2 +(x+y)la puterea a 3

Answer 1

x=3+y
(3+y) la puterea 2-y la puterea 2=12
9+6y+y pătrat -y pătrat=12
9+6y=12
6y=12-9
6y=3
y=1/2=0,5
x=3+0,5
x=3,5

a=(3,5-3)+(3,5+3) la puterea 2+(3,5+3) la puterea 3
a=0,5+12,25+21+9+42,875+3*12,25*3+3*3,5*27+27
a=12,75+21+9+42,875+36,75*3+10,5*27+27
a=33,75+9+42,875+110,25+283,5+27
a=42,75+42,875+110,25+283,5+27
a=85,625+110,25+283,5+27
a=195,875+283,5+27
a=479,375+27
a=506,375

Answer 2

x²-y²=12 ⇔
(x-y)(x+y)=12
x-y=3 ⇒x+y=4;
a=(x-y)+(x+y)²+(x+y)³
a=3+4²+4³
a=3+16+64
a=83