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(x+16)^1/2=x-(x+17)^1/2

1 Answer

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Given the equation


√(x+16)=x-√(x+17)

take the square of both sides then move the square root term to one side to get


\left(√(x+16)\right)^2=\left(x-√(x+17)\right)^2


x+16=x^2-2x√(x+17)+(x+17)


x^2-2x√(x+17)+1=0


x^2+1=2x√(x+17)

Now take the square of both sides again to get


\left(x^2+1\right)^2=\left(2x√(x+17)\right)^2


x^4+2x^2+1=4x^2(x+17)


x^4+2x^2+1=4x^3+68x^2


x^4-4x^3-66x^2+1=0

Use a calculator to find 4 solutions,


x\approx-6.365


x\approx-0.124


x\approx0.123


x\approx10.366

Plugging each of these back into the original equation, you would find that the first 3 solutions are extraneous, so the only solution is


\boxed{x\approx10.366}

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