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# Rearrange to find x -- 0=-2x^-3 + 16 watch

1. Help? How do I go about findig x from this negative cubic? Please show me the steps so I can learn from them?
2. Well if -2x^3+16=0 the 2x^3-16=0 as well (times each side by -1)

Hence you should be OK now?
3. (Original post by Bhansongal98)
Help? How do I go about findig x from this negative cubic? Please show me the steps so I can learn from them?
Recall that 2x^-3 = 2*(1/x^3). You should have everything you need to solve it now.

(Original post by nerak99)
Well if -2x^3+16=0 the 2x^3-16=0 as well (times each side by -1)

Hence you should be OK now?
The OP's problem is the negative exponential, not the negative sign.
4. I've got it down to 8x^3 - 1 but I'm struggling to find a factor
5. 8x^3-1=0 => 8x^3=1 (=) x^3=1/8 (=) x=1/2

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6. (Original post by Bhansongal98)
I've got it down to 8x^3 - 1 but I'm struggling to find a factor
0= -2x^-3+16
(+-2x^-3) 2x^-3=16
(divide by 2) x^-3=8
(x^-3= 1/x³) 1/x³=8
(multiply by x³) 1=8x³
(divide by 8) 1/8=x³
(cube root)x=1/2

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