Question

−6 <3n+9 <21. whats the solution

Answer 1

We have

`-6 < 3n+9 < 21`.

From this we have system of inequality

`</p><p>-6 < 3n+9 \\</p><p>3n+9 < 21`

We have to simplify both inequalities

`</p><p>3n+9 > -6 \Longrightarrow n > -5 \\</p><p>3n+9 < 21 \Longrightarrow n < 4</p><p>`

So we can conclude that

`n > -5 \wedge n < 4 \Longrightarrow x\in(-5,4)`

Hope this helps.