Question

How do you solve the equation `abs(1.2-0.3x)=1.5`?

Answer 1

The equation has 2 solutions: `x_1=-1` and `x_2=9`. See explanation.

Explanation:

First we can see that

`|f(x)|=a iff f(x)=-a vv f(x)=a`

So here we have:

`1.2-0.3x=-1.5 vv 1.2-0.3x=1.5`

Both equalities can be divided by `-0.3`

`-4+x=5 vv -4+x=-5`

Now if we add `4` to both sides of both equations we get the solution:

`x=9 vv x=-1`