Question

How do you solve `10 + x - 2x^2<0`?

Answer 1

We first rewrite this in standard form: `-2x^2+x+10<0`

Since the coefficient of the square is negative, we call this a "mountain"-parabola.

`y=0` gives us `x=2.5 and x=-2`
Since it's a "mountain", our answers lie outside these points, so:
`x<-2 or x>2.5`
graph{10+x-2x^2 [-22.8, 22.83, -11.4, 11.4]}