Question

if a+b = 12 and a2 + b2 = 20 then a.b=

Answer 1

a + b = 12

a² + b² = 20

$<u><i>( a + b )² = a² + b² + 2ab</u></i>$

Putting values in this identity

( 12 )² = 20 + 2ab

144 = 20 + 2ab

2ab = 144 - 20

2ab = 124

ab = 124 / 2

$<b>ab = 62</b>$