Question

How do you solve `z^2-16<0` using a sign chart?

Answer 1

Solution: `-4 < z < 4` In interval notation: `(-4,4)`

Explanation:

`z^2 -16 < 0 or (z+4) (z-4) < 0`. Critical points are `z=-4 , z= 4`

When `z < -4 ;` sign of `(z+4) (z-4) = (-) * (-) = (+) i.e > 0`

When `-4 < z < 4 ;` sign of `(z+4) (z-4) = (+) * (-) = (-) i.e < 0`

When `z > 4 ;` sign of `(z+4) (z-4) = (+) * (+) = (+) i.e > 0`

Solution: `-4 < z < 4`
In interval notation: `(-4,4)` [Ans]