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Solve this equation. `x + 5*sqrt(x) - 36 = 0`

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kristenmarieb... | Student, Grade 10 | Valedictorian

Posted May 6, 2013 at 4:04 AM via web

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Solve this equation.

`x + 5*sqrt(x) - 36 = 0`

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted May 6, 2013 at 4:09 AM (Answer #1)

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The equation `x + 5*sqrt x - 36 = 0` has to be solved.

`x + 5*sqrt x - 36 = 0`

Let `sqrt x = y`

=> `y^2 + 5y - 36 = 0`

=> `y^2 + 9y - 4y - 36 = 0`

=> `y(y + 9) - 4(y + 9) = 0`

=> `(y - 4)(y + 9) = 0`

=> y = 4 and y = -9

y = 4

=> `sqrt x = 4`

=> x = 16

y = -9

=> `sqrt x = -9`

=> x = 81

The solution of the equation are x = 16 and x = 81

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