Question

If $a-b=7,ab=8$, find $a^2+b^2$

Answer 1

We have,

$a-b=7$ …… (1)

$ab=8$ …….. (2)

On squaring both sides of equation (1), we get

${(a-b)}^2={\left(7\right)}^2$

$a^2+b^2-2ab=49$

From equation (2), we get

$a^2+b^2-2\times 8=49$

$a^2+b^2-16=49$

$a^2+b^2=49+16$

$a^2+b^2=65$

Hence, this is the answer.