f(x)=2x^2 -8 What is the value of x if f(x)=0, x>0
This would be a typical B grade GCSE question. Firstly, let's set f(x) to 0 , where now we have 0=2x2-8 . We now need to rearrange to find x. First, move the -8 to the other side of the "=" sign, so now it become +8. We now have the equation 8 =2x2 . Then, move the "2" in front of the x to the other side, so we have 8/2=x2, or 4=x2. To find what x is we can then find the square root of 4, which could be 2, or also negative 2 as when we square a negative we get a positive. As the question states x>0, the answer is x=2.
TD
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