How do you solve and check for extraneous solutions in abs(2t-3) = t|2t3|=t?

1 Answer
Aug 1, 2015

color(red)(t = 3)t=3 is a solution.
color(red)(t = 1)t=1 is an extraneous solution.

SOLVE

|2t-3| = t|2t3|=t

We need to write two different equations without the absolute value symbols and solve for tt.

These equations are:

(1): (2t-3) = t(2t3)=t
(2): -(2t-3) = t(2t3)=t

Solve Equation 1:

2t-3 = t2t3=t

Subtract tt from each side.

t-3 = 0t3=0

Add 33 to each side.

t = 3t=3

Solve Equation 2:

−(2t-3) = t(2t3)=t

Remove parentheses.

-2t+3= t2t+3=t

Add 2t2t to each side.

3 = 3t3=3t

Divide each side by 33.

t = 1t=1

The solutions are t = 1t=1 and t = 3t=3.

CHECK FOR EXTRANEOUS SOLUTIONS:

If t = 1t=1,

|2t-3|=t|2t3|=t
|2(1)-3|= 3|2(1)3|=3
|2-3| = 5|23|=5
|-1| =5|1|=5
1=51=5

This is impossible, so t=1t=1 is an extraneous solution.

If t = 3t=3,

|2t-3| = t|2t3|=t
|2(3) - 3| = 3|2(3)3|=3
|6 - 3| = 3|63|=3
|3| = 3|3|=3
3 = 33=3

t=3t=3 is a solution.