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Question
If an integer is added to its square, the sum is 90. Find the integer with the help of quadratic equation.
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Solution
Let the integer be ‘x’
Given that if an integer is added to its square, the sum is 90.
⇒ 𝑥 + 𝑥2 = 90
⇒ 𝑥 + 𝑥2 − 90 = 0
⇒ 𝑥2 + 10𝑥 - 9𝑥 - 90 = 0
⇒ 𝑥(𝑥 + 10) - 9(𝑥 + 10) = 0
⇒ x = -10 or x = 9
∴ The value of an integer are -10 or 9.
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