QUADRATICS 3

What must be added to x²  + 40x to make the expression a perfect square?

Solution

a=1, b=12,c=?

b² = 4ac

(40)² = 4 x 1 x c

1600 = 4c

1600 = 4c

 4         4

400 = c

Hence number to be added is 400

TRY THIS……………………

What must be added to x²  + 28x to make the expression a perfect square?