Izzie is trying to solve this inequality: 3(t+1)−4t≥−5

After she solves it, she shows it to you and asks you if she did it correctly.

This is the work she completed:

Step 1: 3t+3−4t≥−5
Step 2: −t+3≥−5
Step 3: −t≥−2
Step 4: t≤2


(12 points)
True False
The correct answer should have been t≤8

Izzie made a mistake going from step 3 to step 4

Izzie made a mistake going from step 2 to step 3

Izzie made no mistakes in solving this inequality

Izzie made a mistake going from step 1 to step 2

Izzie should not have changed the inequality symbol from ≥ to ≤

1 answer

Let’s go through Izzie's work step by step to determine if she solved the inequality correctly.

Starting with the original inequality: \[ 3(t + 1) - 4t \geq -5 \]

Step 1: Simplifying the left-hand side \[ 3(t) + 3(1) - 4t \geq -5 \] This simplifies to: \[ 3t + 3 - 4t \geq -5 \]

Result: \[ -t + 3 \geq -5 \] (This matches Step 1 and Step 2 from Izzie's work)

Step 2: Rearranging the terms Subtract 3 from both sides: \[ -t \geq -5 - 3 \] \[ -t \geq -8 \]

Result: \[ -t \geq -8 \] (Here is where Izzie made a mistake from Step 2 to Step 3)

Step 3: Dividing by -1 When you divide or multiply both sides of an inequality by a negative number, you must reverse the inequality sign: \[ t \leq 8 \]

This means that:

  • Izzie's conclusion in Step 4 "t ≤ 2" is incorrect.
  • The correct answer should actually be t ≤ 8.

So, let's analyze Izzie’s assertions:

  1. True: The correct answer should have been t ≤ 8 - This statement is true.
  2. Izzie made a mistake going from step 3 to step 4 - This is also true.
  3. Izzie made a mistake going from step 2 to step 3 - This is true as well (she incorrectly calculated the right-hand side).
  4. Izzie made no mistakes in solving this inequality - This is false.
  5. Izzie made a mistake going from step 1 to step 2 - This is false; her calculations from step 1 to step 2 were correct.
  6. Izzie should not have changed the inequality symbol from ≥ to ≤ - This statement is true, as she did not reverse it when she should have.

So the correct assessments of the statements are as follows:

  • Statement 1: True
  • Statement 2: True
  • Statement 3: True
  • Statement 4: False
  • Statement 5: False
  • Statement 6: True