SOLUTION: x^3+10x=80

Question 821367: x^3+10x=80

Answer by tommyt3rd(5050) (Show Source): You can put this solution on YOUR website!
Assuming you want an approximate real solution we can use Newton's method. Writing f(x)=x^3+10x-80, and f'(x)=3x^2+10 and writing as a sequence we can see:

For a reasonable first guess we can use the fact that when x=3, the LHS of the original equation is 57 and when x=4, LHS=104. So let's split the difference and choose x=3.5
This gives us...

so probably close enough...

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