Question

If x + √x=90; Find the value of x. I know ans. but try to find easy way to solve , any trick help.​

Answer 1

x + √x = 90

x + x^(1/2) = 90

Let y = x^(1/2), so y² = x

y² + y - 90 = 0

(y + 10)(y - 9) = 0

y = -10, 9, so x = 81, 100

81 + √81 = 81 + 9 = 90 (correct)

100 + √100 = 100 + 10 = 110 (incorrect)

So x = 81.