If an integer is added to its square, the sum is 90. Find the integer with the help of quadratic equation.
Let the integer be ‘a’.
Given, an integer is added to its square, the sum is 90
⇒ a + a2 = 90
⇒ a2 + 10a – 9a – 90 = 0
⇒ a(a + 10) – 9(a + 10) = 0
⇒ (a – 9)(a + 10) = 0
⇒ a = -10, 9