Question

The sum and product of two numbers is 10 and 20 respectively. Find the sum of their squares.

• A. 60
• B. 80
• C. 100
• D. 50

Answer 1

The correct option is A

60

Let the two numbers be x and y.

Given: x+y = 10 and xy = 20

We know the identity $(x+y{)}^2$ = $x^2$ +$y^2$ + 2xy

Which gives ${10}^2$ = $x^2$ +$y^2$ + 40

Hence $x^2$ +$y^2$ = 100-40 = 60