Question

Daca a +b =3 si a-b=7, calculati :
a)a2 +2ab+b2 ;
b)a2-b2;
c)Pentru a=5, calculati b2-6b+10

Answer 1

a)
a²+2ab+b²=(a+b)²=3²=9

b)
a+b=3=>a=3-b
a-b=7=>3-b-b=7=>3-2b=7=> -2b=4=>b=-2=>a=5
a²-b²=5²-(-2)²=25-4=21

c)
b²-6b+10=(-2)²-6(-2)+10=4+12+10=26.