Q2 of 83 Page 90

Find the roots of the following equations by the method of perfect square:

x2 + (x + 5)2 = 625

x2 + x2 + 10x + 25 – 625 = 0

⇒ 2x2 + 10x – 600 = 0


Dividing the whole equation by 2, we get,


⇒ x2 + 5x – 300 = 0






⇒(x + 20) = 0 or (x – 15) = 0


⇒ x = – 20 or x = 15


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Divide 20 into two parts such that the sum of the square of the parts is 218.