# If a - b = 3 and $a^2$+ $b^2$= 29, then find the value of ab

 [ A ]    10 [ B ]    12 [ C ]    15 [ D ]    18
 Answer : Option A Explanation : $A^2$+$b^2$=29….(i)And a-b =3….(ii)Now ,squaring both sides of the equation (ii),We have,$(a-b)^2$=$(3)^2$=$a^2$+$b^2$-2ab=9=29-2ab=9 [So,$a^2$+$b^2$=29(given)]=-2ab=-20= ab = $20\over 2$ = 10