Subtracting Integers Prepared by:

Ms. Rinalyn L. Ignacio

Subject: Mathematics 7

Level: Grade 7

Observe the following pictures and then match the pictures opposite to each other.

MournHungry

Good

Bad

Poor

Clean

Dirty

BowNew born

Rich

Study the following patterns.

Subtraction Adding the opposite

5 – 3 = 26 – 2 = 43 – 0 = 3

7 – (-1) = 89 – (-5) =

14-3 – (-1) = -

2-5 – (-2) = -

3

5 + (-3) = 26 + (-2) = 43 + 0 = 37 + 1 = 8

9 + 5 = 14-3 + 1 = -2-5 + 2 = -3

CONCLUSION:The patterns in the mathematical sentences above show that subtracting a number gives the same results as adding its opposite.

Using the Number LineExpress the subtraction problem to addition problem.

Examples:

a. -4-3b. 4-(-3)c. -8 - (-

12)

-4-3 =-4 + (-

3)-

4 – (-3)

= 4 + 3

-8 – (-12) =

-8 + 12

Using Algebra

Tiles

Examples:

(+5) – (+2) =Remove or take away +2 of the tiles:

(+1) – (+1) =

(-4) – (-3) =

(-7) – (-2) =

So,….What’s left?

(+3) – (-5) =

+3 “remove” -5, but you do not have any negatives to remove.

Add zero pairs!

(+3) – (-5) =

Now you can remove -5And, your left with……

Now, try: (-4) – (+1) =

Zero pair

(-4) – (+1) =

Add a zero pair.Now you can remove +1And, your left with……

(-8) – (+3) = 4 – (-7) = -6 – (+9) =

Zero pair

What are the disadvantages of using number line and algebra tiles in subtracting integers?

Rule in Subtracting Integers

In subtracting integer from another integer, add the opposite of the subtrahend to the minuend.

Use the number line to subtract the following integers.

Grp. 1–5 -1 – (-6)

Grp. 6–10 -2 - 7

-1 – (-6) = 5

-2 – 7 = -9

Subtract by using the algebra tiles.

Grp. 1–5 4- (-3)

Grp. 6 –10 -5 – (-2)

Grp. 1–5 4- (-3) = 7

Grp. 6–10 -5 – (-2) = -3

Subtract. Use the rule for subtracting integers.

Grp. 1-4 -11 – 14 Grp. 5-7 18 - 22Grp. 8-10 41-

(-25)

Let’s Check:Grp. 1-4 -11 – 14 = 4 Grp. 5-7 18 – 22 = -4Grp. 8-10 41- (-25) = 66

Let us work in group!Use the number line to

subtract the following integers.

a. 11 – (-5)

b. -6 – (-9)

b. -6 – (-9) = 3

a. 11 – (-5) = 15

Let’s check:

Subtract by using algebra tiles.

c. 5 – (-3)

d. (-3) – (-8)

Let’s check:

c. 5 – (-3) = 8

d. (-3) – (-8) = 5

Subtract. Use the rule for subtracting integers.

e. -29 - 45

f. 18 - 24

g. -20 – (-4)

Let’s check:

e. -29 – 45 = -74

f. 18 – 24 = -6

g. -20 – (-4) = -16

GOSPEL INTEGRATION

Matthew 5:3-10 “The Beatitudes”

Blessed are the poor in spirit, for theirs is the kingdom of heaven. Poor Rich

Blessed are they who mourn, for they will be comforted.

Mourn

New born baby

Blessed are the meek, for they will inherit the land.

Good Bad

Blessed are they who hunger and thirst for righteousness, for they will be satisfied.

Hungry

Bow

Blessed are the merciful, for they will be shown mercy.

Blessed are the clean of heart, for they will see God.

Clean

Dirty

Assignment:Answer page 48-49 of The Next Century Mathematics I (Elementary Algebra) Written Math, A numbers 1-10