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If anyone can help me with how to go about solving these kind of equations i would really appreciate it. :-)

$$\sqrt{36-2x^2} = 4$$

Solve for X

Toby Mak
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Miranda Wolf
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3 Answers3

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$36-2x^2 = 16$

$\frac{36-16}{2} = x^2$

$x= \pm \sqrt{10}.$

rami_salazar
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I would start by looking at how to get rid of the square root sign on the left-hand side of the equation. Then I would look at isolating your variable, i.e. x. What did you attempt already?

user3727648
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Square both sides:

$$36-2x^2=16$$ $$ -2x^2+20=0$$ $$ 2x^2-20=0$$ $$x^2-10=0$$ $$x = ±\sqrt{10}$$

Now we need to check for extraneous solutions. You can then substitute these values of $x$ in the LHS, and check they equal the RHS.

Toby Mak
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  • Thank you Toby! I had got to $$x^2-10=0$$ and then i got stuck. I'm new to Maths. I didn't realise i could have a radical sign in my answer. That's a huge help! – Miranda Wolf Nov 11 '18 at 00:40
  • @MirandaWolf That's why it's always better to show your work! If you had just said that in your question, I would only need the last few lines of my answer. – Toby Mak Nov 11 '18 at 00:43
  • I hadn't worked out the formatting to type my working out on here, but i have now thanks to you. :-) – Miranda Wolf Nov 11 '18 at 02:01