If a+b=9, and a−b=5, find the value of 2(a2+b2).
100
106
94
45
We know 2(a2+b2)=(a+b)2+(a−b)2.
Given a+b=9 and a−b=5.
Substituting the values in the above formula, we get
2(a2+b2)=92+52
=81+25
=106
If (a+b)=5 and ab=6,find the value of a2+b2; a>b