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chapter8.1b
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àï8.1èAdding Rational Numbers.
äèPlease add the following Rational Numbers.
âSêè1)ê 3 + 4è=è7
êêè 2)ê -5 + (-6)è=è-11
êêè 3)ê 8 + (-5)è=è3
êêè 4)ê -7 + 5è=è-2
éSëThe Whole Numbers were introduced in Chapter 1.ïThis set
was extended to the Positive Fractions in Chapter 2.ïThe next step
is to extend this set to the set of Rational Numbers.ïThe Rational
Numbers include all of the negative fractions, zero, and the positive
fractions.êêèRational Numbers
#êê - ╦ï- ╩ï- ╔è ╚è ╔è ╩è ╦è ╠
êï. . .è1è 1è 1è 1è 1è 1è 1è 1ï. . .
#êê - ╦ï- ╩ï- ╔è ╚è ╔è ╩è ╦è ╠
êï. . .è2è 2è 2è 2è 2è 2è 2è 2ï. . .
#êê - ╦ï- ╩ï- ╔è ╚è ╔è ╩è ╦è ╠
êï. . .è3è 3è 3è 3è 3è 3è 3è 3ï. . .
êêê .êêêè.
êêê .êêêè. (the pattern continues)
We would like to look at the Addition Operation on this important set of
numbers which is sometimes called the "signed numbers".ïThe Addition
Operation is broken down into two cases.ïThe first case occurs when
adding two numbers from the same side, i.e. when both numbers are
positive or when both numbers are negative.ïThis case is covered in
Rule 1.
RULE 1ïTo add two numbers that are either both positive or both
negative, think of them as both positive and add them together as we did
positive numbers in Chapters 1 and 2.ïThen attach the original "sign"
that they both had in common.èExamplesï3 + 4 = 7ë-5 + (-6) = -11
The second case involves adding two numbers when one number is positive
and the other number is negative.ïThis case is covered by Rule 2.
RULE 2ïTo add two numbers with different signs, think of them as both
positive and subtract the smaller from the larger as we did positive
numbers in Chapters 1 and 2.ïThen attach the original "sign" of the
larger number.ê Examplesè 8 + (-5) = 3,è -7 + 5 = -2
ï1
êêêë Add,è4 + 16.
êA)ï-12êè B)ï20êëC)ï12êè D)ïå
ü
êêêê4 + 16è=è20
ÇïB
ï2
êêêë Add,è-5 + (-12).
êA)ï-17êè B)ï17êëC)ï-7êè D)ïå
ü
êêêè -5 + (-12)è=è-17
ÇïA
ï3
êêêë Add,è9 + (-3).
êA)ï-6êëB)ï12êëC)ï6êëD)ïå
ü
êêêë 9 + (-3)è=è6
ÇïC
ï4
êêêë Add,è6 + (-8).
êA)ï-14êè B)ï-2êëC)ï14êè D)ïå
ü
êêêë 6 + (-8)è=è-2
ÇïB
ï5
êêêë Add,è-12 + 8.
êA)ï4êë B)ï20êëC)ï-4êè D)ïå
ü
êêêë -12 + 8è=è-4
ÇïC
ï6
êêêë Add,è-7 + 9.
êA)ï2êë B)ï-16êè C)ï-2êè D)ïå
ü
êêêë -7 + 9è=è2
ÇïA
ï7
êêêë Add,è-6 + (-15).
êA)ï-21êè B)ï-9êëC)ï9êëD)ïå
ü
êêêë -6 + (-15)è=è-21
ÇïA
ï8
êêêë Add,è-14 + (-23).
êA)ï-9êëB)ï-37êè C)ï9êëD)ïå
ü
êêêë -14 + (-23)è=è-37
ÇïB
ï9
êêêë Add,è(.6) + (-1.4).
êA)ï.8êëB)ï2.0êè C)ï-.8êèD)ïå
ü
êêêë (.6) + (-1.4)è=è-.8
ÇïC
ï10
êêêë Add,è-4.5 + 2.7.
êA)ï2.3êè B)ï-1.8êèC)ï-7.2êïD)ïå
ü
êêêë -4.5 + 2.7è=è-1.8
ÇïB
ï11
êêêë Add,è14 + 0.
êA)ï14êëB)ï15êëC)ï0êëD)ïå
üè Zero is called the "additive identity".ïIt has the property
that when it is added to any number, you get the original number.
êêêê14 + 0è=è14
ÇïA
ï12
êêêë Add,è-8 + 8.
êA)ï-16êè B)ï0êë C)ï8êëD)ïå
üè The two numbers "8" and "-8" are "additive inverses" of each
other.ïAdditive inverses cancel each other out when added and you get
zero.
êêêê-8 + 8è=è0
ÇïB
#ï13êêêï3è┌ï2 ┐
#êêêë Add,è─ + │- ─ │
#êêêêë 5è└ï5 ┘
êêêêè3êê 1
#êA)ï1êë B)ï- ─êè C)ï─êëD)ïå
êêêêè5êê 5
ü
#êêêê3è┌ï2 ┐ê 1
#êêêê─ + │- ─ │è=è ─
#êêêê5è└ï5 ┘ê 5
ÇïC
#ï14êêêï3è┌ï5 ┐
#êêêë Add, - ─ + │- ─ │
#êêêêë 8è└ï8 ┘
êêêêè5êêè5
#êA)ï-1êëB)ï- ─êè C)ï- ─êèD)ïå
êêêêè8êêè8
ü
#êêêê3è┌ï5 ┐êï8
#êêêë- ─ + │- ─ │è=è- ─ = -1
#êêêê8è└ï8 ┘êï8
ÇïA
#ï15êêêï4è┌è8 ┐
#êêêë Add,ï── + │- ── │
#êêêêë15è└ï15 ┘
êë 12êêè4êê16
#êA)ï- ──êèB)ï- ──êèC)ï──êè D)ïå
êë 15êêï15êê15
ü
#êêêê4è┌è8 ┐êè4
#êêêë ── + │- ── │è=è- ──
#êêêë 15è└ï15 ┘êï15
ÇïB
ï16êêêï2è11
#êêêë Add, - ─ + ──.
êêêêë 3è15
êë 2êêï1êêè4
#êA)ï- ─êè B)ï──êëC)ï──êè D)ïå
êë 3êê 15êêï15
ü
êêêë 2è11êè10è11ë 1
#êêêè - ─ + ──è=è - ── + ──ï=ï──
êêêë 3è15êè15è15ë15
ÇïB
ï17êêêï3è1
#êêêë Add,è─ + ─ .
êêêêë 4è3
êê1êê5êêè11
#êA)ï1 ──êèB)ï─êë C)ï──êè D)ïå
êë 12êê4êêè12
ü
êè 3è1ê 9è 4ê13êë 1
#êè ─ + ─è=è── + ──è=è──è orè 1 ──
êè 4è3ê12è12ê12êë12
ÇïA
#ï18êêêï3è┌è2 ┐
#êêêë Add, - ─ + │- ── │.
#êêêêë 5è└ï15 ┘
êè 1êêë11
#êA)ï─êë B)ï- ──êèC)ï- 3êèD)ïå
êè 5êêë15
ü
#êè 3è┌è2 ┐êè9è┌è2 ┐êï11
#êï- ─ + │- ── │è=è- ── + │- ── │è=è- ──
#êè 5è└ï15 ┘êï15è└ï15 ┘êï15
ÇïB
ï19
êêêë Add,è-3 + 5 + (-8).
êA)ï12êëB)ï-16êè C)ï- 6êèD)ïå
ü
êêêê -3 + 5 + (-8)
êêêêè 2 + (-8)
êêêêë -6
ÇïC
ï20êêêë1ê2
#êêêë Add,è-3 ─ï+ï2 ─.
êêêêêï8ê3
êë 11êêè5êêï7
#êA)ï- ──êèB)ï-2 ─êèC)ï- ─êèD)ïå
êë 24êêè8êêï8
ü
êè 1ê2êï25è 8êï75ë64êï11
#ê -3 ─ï+ï2 ─è=è- ──ï+ ─è=è- ──ï+ï──è=è- ──
êè 8ê3êè8è 3êï24ë24êï24
ÇïA