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chapter9.2b
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1993-09-25
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àï9.2ëCombining Like Terms
äèPlease combine the like terms in the following Variable
Expressions.
âèCombine like terms.
êêêè 3x + 5x + 6y - 3y
êêêè3x + 5x + 6y + (-3y)
êêêï(3x + 5x) + (6y + (-3y))
êêêï(3 + 5)x + (6 + (-3))y
êêêêï8x + 3y
éSè "Like Terms" are terms that have the same letters with the
same exponents.ïIn the expression, 3x + 5x + 6y - 3y, the terms "3x"
and "5x" are like terms.ïAlso, "6y" and "-3y" are like terms.ïLike
terms can be combined by adding or subtracting the coefficients (the
numbers out in front of the variable) using the rules for signed numbers
and then attaching the common letter.
For example, "3x" and "5x" can be combined by adding the coefficients "3"
and "5" and attaching the letter "x".
êêêï3x + 5xï=ï(3 + 5)xï= 8x
Also, the "6y" and "-3y" can be combined by subtracting the coefficients
and attaching the "y".
êê 6y - 3yï=ï6y + (-3y)ï=ï(6 + (-3))yï=ï3y
This proceedure is usually done in the following manner.
êêêë3x + 5x + 6y - 3y
êêêè 3x + 5x + 6y + (-3y)
Group the like terms using parençs.
êêêï(3x + 5x) + (6y + (-3y))
Combine the coefficients using the rules for signed numbers.
êêêï(3 + 5)x + (6 + (-3))y
êêêêè8x + 3y
This is as far as you can go, because the terms "8x" and "3y" are Unlike
Terms and can not be combined.
1è Combine like terms.
êêêè 8x + 5x + 7y - 4y
ë A)ï10x - 4yë B)ï13x + 3yë C)ï3x - 3yë D)ïå
ü
êêêè 8x + 5x + 7y - 4y
êêêè8x + 5x + 7y + (-4y)
êêê (8x + 5x) + (7y + (-4y))
êêê (8 + 5)x + (7 + (-4))y
êêêêï13x + 3y
Ç B
2è Combine like terms.
êêêè 4a + 2b - 3a - 6b
ë A)ïa - 4bê B)ï7a - 8bêC)ïa - 8bêD)ïå
ü
êêêè 4a + 2b - 3a - 6b
êêê 4a + 2b + (-3a) + (-6b)
êêê(4a + (-3a)) + (2b + (-6b))
êêê(4 + (-3))a + (2 + (-6))b
êêêê 1a + (-4b)
êêêêèa - 4b
Ç A
3è Combine like terms.
êêêè 11x - 4x + 8y - 3y
ë A)ïx + 10yêB)ï7x + 5yêC)ï3x - 4yë D)ïå
ü
êêêè 11x - 4x + 8y - 3y
êêê 11x + (-4x) + 8y + (-3y)
êêë (11x + (-4x)) + (8y + (-3y))
êêê (11 + (-4))x + (8 + (-3))y
êêêêè7x + 5y
Ç B
4è Combine like terms.
êêêè3a + 4b + 6a + 4c + b
è A)ï9a + 4b + 4cè B)ï9a + 5b + 4cè C)ï9a + 8bë D)ïå
ü
êêêè3a + 4b + 6a + 4c + b
êêê (3a + 6a) + (4b + b) + 4c
êêêï(3 + 6)a + (4 + 1)b + 4c
êêêê 9a + 5b + 4c
Ç B
5è Combine like terms.
#êêêè2xì + 3xì + 5x - 2x
#è A)ï5xì + 3xê B)ï8xìêèC)ï5xÅ + 3xëD)ïå
ü
#êêêè2xì + 3xì + 5x - 2x
#êêêï2xì + 3xì + 5x + (-2x)
#êêê (2xì + 3xì) + (5x + (-2x))
#êêêï(2 + 3)xì + (5 + (-2))x
#êêêêï5xì + 3x
Ç A
6è Combine like terms.
#êêêè5xì - 6xì + 4yì - 7yì
#è A)ï-2xì + 3yìë B)ï2xì - 3yìè C)ï-xì - 3yìè D)ïå
ü
#êêêè5xì - 6xì + 4yì - 7yì
#êêêï5xì + (-6xì) + 4yì + (-7yì)
#êêê (5xì + (-6xì)) + (4yì + (-7yì))
#êêêï(5 + (-6))xì + (4 + (-7))yì
#êêêêï-1xì +(-3yì)
#êêêêè-xì - 3yì
Ç C
7è Combine like terms.
êêêè4a + 7b + 3b - 4a
è A)ï8a - 7bêïB)ï8a + 4bë C)ï10bêïD)ïå
ü
êêêë 4a + 7b +3b - 4a
êêêè 4a + 7b + 3b + (-4a)
êêêè(4a + (-4a)) + (7b + 3b)
êêêêè 0 + 10b
êêêêë 10b
Ç C
8è Combine like terms.
êêêè2a + 3b + 5a - 3b - 7a
è A)ï0êê B)ï14aêèC)ï7bêèD)ïå
ü
êêêè 2a + 3b + 5a - 3b - 7a
êêêè2a + 3b + 5a + (-3b) + (-7a)
êêêï(2a + 5a + (-7a)) + (3b + (-3b))
êêêï(2 + 5 + (-7))a + (3 + (-3))b
êêêêë 0a + 0b
êêêêêï0
Ç A
9è Combine like terms.
êêêè12x - 3y - 2x - 10y
è A)ï8x + 12yê B)ï10x - 13yë C)ï3x - 7yëD)ïå
ü
êêêë12x - 3y - 2x - 10y
êêêï12x + (-3y) + (-2x) + (-10y)
êêê (12x + (-2x)) + (-3y + (-10y))
êêê (12 + (-2))x + (-3 + (-10))y
êêêêï10x + (-13)y
êêêêè10x - 13y
Ç B
10è Combine like terms.
êêêë-12p - 15p + q
è A)ï-27êë B)ï-26pêè C)ï-27p + qè D)ïå
ü
êêêë -12p - 15p + q
êêêè (-12p) + (-15p) + q
êêêè (-12 + (-15))p + q
êêêêè-27p + q
Ç C