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chapter8.3b
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àï8.3ëMultiplying Rational Numbers.
äè Please Multiply the following Rational Numbers.
âSêï1)êè 3 ∙ 4è=è12
êêè2)êè (-5) ∙ (-6)è=è30
êêè3)êè 8 ∙ (-5)è=è-40
êêè4)êè -7 ∙ 5è=è-35
éSëThere are two rules for Multiplying Rational Numbers.ïWe
will call them Rule 4 and Rule 5.
RULE 4ëIn order to multiply two Rational Numbers that are either
both positive or both negative, just multiply them as though they are
both positive numbers and attach a plus sign to the answer.
ê Examplesê 1)è3 ∙ 4è=è12
êêêè2)è(-5) ∙ (-6)è=è30
RULE 5ëIn order to multiply two Rational Numbers that have different
signs, just multiply them as though they are both positive and then
attach a minus sign to the answer.
êExamplesêï1)è8 ∙ (-5)è=è-40
êêêè2)è-7 ∙ 5è=è-35
ï1
êêêëMultiply,ï4 ∙ 16 .
ë A)ï20êëB)ï64êëC)ï84êëD)ïå
ü
êêêë 4 ∙ 16è=è64
Ç B
ï2
êêêè Multiply,ï-5 ∙ (-12).
ë A)ï17êëB)ï-60êè C)ï60êëD)ïå
ü
êêêë-5 ∙ (-12)è=è60
Ç C
ï3
êêêëMultiply,ï9 ∙ (-3).
ë A)ï-27êè B)ï27êëC)ï-12êè D)ïå
ü
êêêë9 ∙ (-3)è=è-27
Ç A
ï4
êêêëMultiply,ï6 ∙ (-8).
ë A)ï-14êè B)ï-48êè C)ï48êëD)ïå
ü
êêêë6 ∙ (-8)è=è-48
Ç B
ï5
êêêë Multiply,ï-12 ∙ 8.
ë A)ï96êëB)ï74êëC)ï-96êè D)ïå
ü
êêêë-12 ∙ 8è=è-96
Ç C
ï6
êêêë Multiply,ï-7 ∙ 9.
ë A)ï-63êè B)ï-16êè C)ï16êëD)ïå
ü
êêêë-7 ∙ 9è=è-63
Ç A
ï7
êêêè Multiply,ï-6 ∙ (-15).
ë A)ï-90êè B)ï90êëC)ï21êëD)ïå
ü
êêêë-6 ∙ (-15)è=è90
Ç B
ï8
êêêè Multiply,ï-14 ∙ (-23).
ë A)ï296êè B)ï-322êèC)ï322êè D)ïå
ü
êêêè -14 ∙ (-23)è=è322
Ç C
ï9
êêêèMultiply,ï(.6) ∙ (-1.4).
ë A)ï2.6êè B)ï-2.6êèC)ï-.84êèD)ïå
ü
êêêè(.6) ∙ (-1.4)è=è-.84
Ç C
ï10
êêêèMultiply,ï-4.5 ∙ 2.7.
ë A)ï8.6êè B)ï-12.15ê C)ï-10.43ê D)ïå
ü
êêêè-4.5 ∙ 2.7è=è-12.15
Ç B
ï11
êêêë Multiply,ï-8 ∙ 8.
ë A)ï16êëB)ï-64êè C)ï-16êè D)ïå
ü
êêêë -8 ∙ 8è=è-64
Ç B
ï12
êêêë Multiply,ï14 ∙ 0.
ë A)ï-14êè B)ï14êëC)ï0êë D)ïå
ü
êêêê14 ∙ 0è=è0
Ç C
#ï13êêê 3è┌è2 ┐
#êêê Multiply,ï─ ∙ │ - ─ │.
#êêêêë5è└è5 ┘
êë 6êêï6êê 1
#ë A)ï- ──êèB)ï- ─êè C)ï─êë D)ïå
êë25êêï5êê 3
ü
#êêêï3è┌è2 ┐êè6
#êêêï─ ∙ │ - ─ │è=è- ──
#êêêï5è└è5 ┘êï25
Ç A
#ï14êêêè3è┌è8 ┐
#êêê Multiply,ï- ─ ∙ │ - ─ │.
#êêêêê8è└è5 ┘
êè5êêë24êê3
#ë A)ï─êë B)ï- ──êèC)ï─êë D)ïå
êè8êêë40êê5
ü
#êêêï3è┌è8 ┐ê3
#êêê- ─ ∙ │ - ─ │è=è─
#êêêï8è└è5 ┘ê5
Ç C
ï15
#êêêë Multiply,ï(-2)Å.
ë A)ï16êëB)ï- 16êèC)ï- 8êè D)ïå
ü
#êêè(-2)Åè=è(-2)∙(-2)∙(-2)∙(-2)è=è16
Ç A
ï16
#êêêë Multiply,ï- 2Å.
ë A)ï16êëB)ï- 16êèC)ï- 8êè D)ïå
ü
#êê - (2)Åè=è- (2)∙(2)∙(2)∙(2)è=è- 16
Ç B
ï17
êêêèMultiply,ï-2 ∙ 3 ∙ (-5).
ë A)ï30êëB)ï- 15êèC)ï- 10êèD)ïå
ü
êê -2 ∙ 3 ∙ (-5)è=è-6 ∙ (-5)è=è30
Ç A
ï18
êêè Multiply,ï-3 ∙ (-4) ∙ (-2) ∙ (-5)
ë A)ï-120êèB)ï-84êè C)ï120êè D)ïå
ü
ë-3∙(-4)∙(-2)∙(-5)è=è12∙(-2)∙(-5)è=è-24∙(-5)è=è120
Ç C