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chapter8.4b
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àï8.4è Dividing Rational Numbers.
äèPlease Divide the following Rational Numbers.
âSêè1)ê 12 ÷ 4è =è 3
êêè 2)ê -15 ÷ (-3)è =è 5
êêè 3)ê -24 ÷ 6è =è -4
êêè 4)ê 28 ÷ (-4)è =è -7
éSëThere are two rules for dividing Rational Numbers.ïThese
rules will be Rules 6 and 7.
RULE 6ëIn order to divide two Rational Numbers that are either both
positive or both negative, just divide them as though they are both
positive numbers and attach a plus sign to the answer.
êèExamplesê1)è12 ÷ 4è=è3
êêêè 2)è-15 ÷ (-3)è=è5
RULE 7ëIn order to divide two Rational Numbers that have different
signs, just divide them as though they are both positive and then attach
a minus sign to the answer.
êè Exampleê 1)è-24 ÷ 6è=è-4
êêêë2)è28 ÷ (-4)è=è-7
1êêêê 35
#êêêêDivide,è──.
êêêêêè 5
êA)ï7êè B)ï5êëC)ï-8êèD)ïå
ü
êêêêï35
#êêêêï──è =è 7
êêêêè5
Ç A
2
êêêêDivide,è-45 ÷ 9.
êA)ï5êè B)ï-5êëC)ï-8êèD)ïå
ü
êêêë-45 ÷ 9è =è -5
Ç B
3êêêê -40
#êêêêDivide,è───.
êêêêêè 10
êA)ï20êèB)ï4êë C)ï-4êèD)ïå
ü
êêêê -40
#êêêê ───è =è -4
êêêêï10
Ç C
4
êêêêDivide,è-72 ÷ 9
êA)ï-12êïB)ï16êëC)ï-8êèD)ïå
ü
êêêë -72 ÷ 9è =è -8
Ç C
5
êêêëDivide,è80 ÷ (-10).
êA)ï12êèB)ï-8êëC)ï-15êïD)ïå
ü
êêêë 80 ÷ (-10)è =è -8
Ç B
6êêêê -14
#êêêêDivide,è───.
êêêêêë0
êA)ïundefinedèB)ï0êë C)ï- 14ê D)ïå
ü
ë Division by zero is undefined and is therefore not permissible.
êêêê -14
#êêê Thus,ï───èis undefined.
êêêêè0
Ç A
7êêêêï0
#êêêêDivide,è──.
êêêêêè23
êA)ïundefinedë B)ï0êèC)ï23êèD)ïå
ü
ë Zero divided by twenty-three is well defined and is therefore
permissible.
êêêêï0
#êêêê ──è =è 0
êêêê 23
Ç B
8êêêê -14
#êêêêDivide,è───.
êêêêêè 1
êA)ï-7êè B)ï1êèC)ï-14êïD)ïå
ü
êêêê -14
#êêêê ───è =è -14
êêêêï1
Ç C
9êêêêï2è4
#êêêë Divide,è- ─ ÷ ─.
êêêêêè 3è9
êè 4êêè 3êê3
#êA)ï─êëB)ï- ─ê C)ï- ─êïD)ïå
êè 3êêè 2êê5
ü
êê2è4êï2è9êï1è3êï3
#êë- ─ ÷ ─è=è- ─ ∙ ─è=è- ─ ∙ ─è=è- ─
êê3è9êï3è4êï1è2êï2
Ç B
10êêêê.25
#êêêêDivide,è───.
êêêêêè-.5
êA)ï- .5êïB)ï.5êïC)ï.005ê D)ïå
ü
êêêêï.25
#êêêêï───è =è -.5
êêêêï-.5
Ç A
# 11êêêë7è┌è14 ┐
#êêêèDivide,è- ─ ÷ │ - ── │
#êêêêê 9è└è 3 ┘
êê5êê3êë 1
#êA)ï- ──êïB)ï──êïC)ï─êè D)ïå
êë 14êë 14êë 6
ü
#êè 7è┌è14 ┐êï7è┌è3┐êï1è┌ï1┐ë1
#êï- ─ ÷ │ - ── │è=è- ─ ∙ │- ──│è=è- ─ ∙ │- ─│ï=ï─
#êè 9è└è 3 ┘êï9è└ï14┘êï3è└ï2┘ë6
Ç C
12êêêê-27
#êêêêDivide,è───.
êêêêêè 0
ë A)ï-27êèB)ïundefinedê C)ï0êèD)ïå
ü
êêêë- 27
#êêêë ───ïis undefined.
êêêê0
Ç B
13êêêê 0
#êêêêDivide,è───.
êêêêêè100
ë A)ï0êèB)ïundefinedê C)ï100êïD)ïå
ü
êêêê0
#êêêë ───è =è 0
êêêë 100
Ç A
14
êêêè Divide,è-.8 ÷ (-.4)
êA)ï2êëB)ï-.2ê C)ï.02êïD)ïå
ü
êêêè -.8 ÷ (-.4)è=è2
Ç A
# 15êêêêï5è┌ï3 ┐
#êêêêDivide,è- ─ ÷ │- ─ │.
#êêêêêë8è└ï4 ┘
êè 8êêè 3êë5
#êA)ï─êëB)ï- ─ê C)ï─êè D)ïå
êè 3êêè 8êë6
ü
#êï5è┌ï3 ┐êï5è┌ï4 ┐êï5è┌ï1 ┐ê5
#ê- ─ ÷ │- ─ │è=è- ─ ∙ │- ─ │è=è- ─ ∙ │- ─ │è=è─
#êï8è└ï4 ┘êï8è└ï3 ┘êï2è└ï3 ┘ê6
Ç C