Question

Am o nedumerire, la o problema de la mate.

Daca a+b=7, a*b=10 atunci A patrat + B patrat =?

Cum as putea rezolva!?

Answer 1

A+b=7 5+2=7 A*b=10 5*2=10 25+4=29

Answer 2

$a+b=7 \\ a\cdot b=10 \\ a^2+b^2=? \\ a+b=7 \Rightarrow a^2+2ab+b^2=49 \\ a^2+2 \cdot 10+b^2=49 \\ a^2+20+b^2=49 \\ a^2+b^2=49-20 \\ a^2+b^2=29$