if a - b = 3 and a ( power 2 ) + b ( power 2 ) = 39 , find the value of ab .
"2 ab = ( a ( power 2 ) + b ( power 2 ) - ( a - b ) ( power 2 ) = 39 - 9 = 30 ab = 15 . answer is a ."
divide(subtract(39, power(3, 2)), 2)