Find a real solution for: x^3+10x=80

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...