Alg1 - 0.2 Adding and Subtracting Rational Numbers

0.2 NOTES Adding, and Subtracting Numbers.pdf

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0.2 HW Adding, and Subtracting Numbers.pdf

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Adding negative numbers:

Example 1: Add -3 to +5.

• Draw a number line and mark +5 on it.

• Since we're adding a negative (-3), instruct students to move 3 positions to the left.

• They will land on +2.

• Therefore, 5 + (-3) = 2.

Subtracting negative numbers:

Example 2: Subtract -4 from -2.

• Draw a number line and mark -2 on it.

• Since we're subtracting a negative (-4), it's like adding 4. Instruct students to move 4 positions to the right.

• They will land on +2.

• Therefore, -2 - (-4) = 2 (notice how this is the same answer as adding 4 to -2).

Key takeaway - Treat subtracting a negative number as adding a positive:

Example 3: Simplify and solve: 7 - (-6).

• Rewrite the problem as 7 + 6 (because subtracting -6 is the same as adding 6).

• Solve: 7 + 6 = 13.