Question

learning goal 7.3: students will use integer chips to represent and perform integer addition

1. which situation could be represented by the numerical expression -8 + 12?

a. jake deposited $4 into his account and withdrew $12.
b. benjamin withdrew $8 from his account and withdrew another $12.
c. carol deposited $8 into her account and withdrew $10.
d. debbie withdrew $8 from her account and deposited $12.

1. saoirse created the sketch below to represent the expression -5 + (-4).

image of integer chips: 5 negative chips, 4 positive chips
her sketch is incorrect. explain why, and create a new sketch to find the sum.

Explanation:

Question 1

Step1: Analyze each option

• Option A: Deposit $4 (positive) and withdraw $12 (negative) → Expression: \(4 + (-12)\) or \(-12 + 4\), not \(-8 + 12\).
• Option B: Withdraw $8 (negative) and withdraw $12 (negative) → Expression: \(-8 + (-12)\), not \(-8 + 12\).
• Option C: Deposit $8 (positive) and withdraw $10 (negative) → Expression: \(8 + (-10)\) or \(-10 + 8\), not \(-8 + 12\).
• Option D: Withdraw $8 (negative) and deposit $12 (positive) → Expression: \(-8 + 12\), matches.

The expression \(-5 + (-4)\) means adding two negative integers. Integer chips: negative chips (usually red) represent negative numbers, positive chips (usually yellow) represent positive numbers. For \(-5 + (-4)\), we need 5 negative chips and 4 negative chips, not positive chips. Saorse included positive chips, which is incorrect.
New sketch: Draw 5 negative chips (e.g., red circles with \(-\)) and 4 negative chips. Total negative chips: \(5 + 4 = 9\), so \(-5 + (-4) = -9\).

Answer:

D. Debbie withdrew $8 from her account and deposited $12.

Question 2