Question

Jill solved the inequality -x/4 < (x+2)/3

Her solution is shown:

Step 1 : -3x<4x+8
Step 2: -3x-4x <8
Step 3: -7x<8
Step 4: x< -8/7

Explain the mistake Jill made while solving for x.


I don't see anything wrong... is it a trick questions???

Answer 1

Answer:

Jill did not change the symbol of inequality from minor (< ) to major (>) in the Step 4

Step-by-step explanation:

we have

$-\frac{x}{4}  < \frac{x+2}{3}$

step 1

Multiply by 12 both sides

$(12)(-\frac{x}{4})  < (12)(\frac{x+2}{3})$

$-3x < 4(x+2)$

$-3x < 4x+8$

step 2

Group terms

$-3x-4x < 8$

step 3

Combine like terms

$-7x < 8$

step 4

Divide by -7 both sides

$x > -8/7$

Remember that when you multiply an inequality by -1 the < symbol changes to the > symbol  

so

Jill did not change the symbol of inequality from minor (< ) to major (>) in the Step 4