Let's solve
[tex]\\ \rm\rightarrowtail -2.5(1.4+3.1)+6.9(-4.3)[/tex]
[tex]\\ \rm\rightarrowtail -3.5-7.75-29.67[/tex]
[tex]\\ \rm\rightarrowtail -11.25-29.67[/tex]
[tex]\\ \rm\rightarrowtail -40.92[/tex]
Both did error in signs
Answer:
Given expression:
-2.5(1.4+3.1) + 6.9(-4.3)
Student P
Step 1: Β -3.5 + 7.75 + 6.9(-4.3)
Step 2: -3.5 + 7.75 - 29.67
Step 3: 7.75 - 3.5 - 29.67
Step 4: -25.42
Student P made an error in step 1. Β When expanding the first part of the expression, they forgot the negative sign when multiplying -2.5 by 3.1. Β
So Step 1 should be: Β -3.5 - 7.75 + 6.9(-4.3). Β
This error then impacted all following steps and gave an incorrect final solution.
Student Q
Step 1: -3.5 - 7.75 + 6.9(-4.3)
Step 2: -3.5 - 7.75 - 29.67
Step 3: -(3.5 - 7.75 - 29.67)
Step 4: -(-33.92)
Step 5: 33.92
Student Q made an error in step 3. Β When placing the numbers in parentheses and placing a negative sign outside the parentheses, they should have changed the two negative signs inside the parentheses to positives.
So Step 3 should be: -(3.5 + 7.75 + 29.67). Β
This error then impacted all following steps and gave an incorrect final solution.
Correct steps and solution
Step 1: Β -3.5 - 7.75 + 6.9(-4.3)
Step 2: -3.5 - 7.75 - 29.67
Step 3: -(3.5 + 7.75 + 29.67)
Step 4: -(40.92)
Step 5: -40.92
