Question

a-b=5 , ab=16 find a+b

Answer 1

a-b=5
then
${(a - b)}^{2} = 25$
that is
${a}^{2} + {b}^{2} - 2ab = 25$
put value of ab and we get
${a}^{2} + {b}^{2} = 57$
now whole square a+b
${(a + b)}^{2} = {a}^{2} + {b}^{2} + 2ab$
that is
${(a + b)}^{2} = 57 + 32 = 89$
$a + b = \sqrt{89}$