Question

Solve |x + 9| < 12.
{x| -3 < x < 21}
{x| -21 < x < 3}
{x| -12 < x < 12}
{x| -3 < x < 3}

Answer 1

this means that:
\[x+9 <\pm 12\]
can you proceed from here?

Answer 2

isnt it {x| -3 < x < 3}

Answer 3

?

Answer 4

lets work step by step and see:
x+9 <-12
x<-12-9
x<-21

x+9 <12
x<12-9
x<3 or x>-3

combining the two inequalities:
-3<x<-21