home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Multimedia Algebra
/
Algebra1.iso
/
ALGEBRA1
/
CHAPTER6.5T
< prev
next >
Wrap
Text File
|
1994-02-15
|
3KB
|
167 lines
165
à 6.5 Solving 2nd Degree Equations by Factoring
äïPlease solve the following second degree equations by the
êêfactoring method.
#âêêè Solve 2xì - 5x - 3 = 0
#ë (2x + 1)(x - 3) = 0êè 2x + 1 = 0è │è x - 3 = 0
#êêêêê 2x = -1ê│è x = 3
#êêêêêê 1ë │
#êêêêêïx = - ─ë │
#êêêêêê 2ë │
éS
#In order to solve the quadratic equation, 2xì - 5x - 3 = 0,ïit is first
necessary to factor the trinomial on the left side of the equation.
#êêêê2xì - 5x - 3 = 0
êêêê(2x + 1)(x - 3) = 0
Since the product of (2x + 1) and (x - 3) is zero, at least one or both
of ç factors must be zero.ïBy the zero-factor property we can set
each factor equal to zero.
#êêêï2x + 1 = 0ï│ïx - 3 = 0
These two equations can then be solved using linear methods.
#êêê2x + 1 = 0è │è x - 3 = 0
#êêê2x = -1ê│è x = 3
#êêêê1ë │
#êêê x = - ─ë │
#êêêê2ë │
êêêêï1
#The two solutions are 3 and - ─
êêêêï2
1
#êêêèSolveïxì - 2x - 15 = 0
ëA)ï{-3,5}ê B)ï{4,3}êïC)ï{1,15}ê D) {-5,3}
#üêêê xì - 2x - 15 = 0
êêêë (x + 3)(x - 5) = 0
#êêêèx + 3 = 0ï│ïx - 5 = 0
#êêêêx = -3 │ïx = 5
êêêêè {-3,5}
Ç A
2
#êêêèSolveïxì - 6x + 9 = 0
êA)ï{-9,1}ê B)ï{9,1}êïC)ï{3,6}ê D) {3}
#üêêê xì - 6x + 9 = 0
êêêë (x - 3)(x - 3) = 0
#êêêèx - 3 = 0ï│ïx - 3 = 0
#êêêêx = 3ï│ïx = 3
êêêêë {3}
Ç D
3
#êêêè Solveïxì - 16 = 0
êA)ï{-8,2}ê B)ï{-4,4}ê C)ï{16,1}êD) {2,8}
#üêêêè xì - 16 = 0
êêêë (x + 4)(x - 4) = 0
#êêêèx + 4 = 0ï│ïx - 4 = 0
#êêêêx = -4 │ïx = 4
êêêêè {-4,4}
Ç B
4
#êêêïSolveè2xì + 5x - 12 = 0
êè 3êêë3
#ë A)ï{─,-4}ê B)ï{- ─,4}ê C)ï{3,4}êD) {2,6}
êè 2êêë2
#üè 2xì + 5x - 12 = 0ë ┌─>è2x - 3 = 0ï│ïx + 4 = 0
#êè(2x - 3)(x + 4) = 0ï──┘êï2x = 3ï│ïx = -4
#êêêêêêêï│
#êêêêêêë 3ï│
#êêêêêêïx = ─ï│
#êêêêêêë 2ï│
Ç A
5
#êêêè Solveè2xì - 3x = 0
êêêêï3êêè 3êêno
#ë A)ï{2,3}êïB)ï{ ─ }êïC)ï{0,─ }êD) solution
êêêêï2êêè 2
#üè 2xì - 3x = 0êè ┌─>ê x = 0ï│ï2x - 3 = 0
#êèx(2x - 3) = 0ê ──┘êêè│ï2x = 3
#êêêêêêêï│
#êêêêêêêï│ê3
#êêêêêêêï│èx = ─
#êêêêêêêï│ê2
Ç C
6
#êêêèSolve 2xì - 6x - 20 = 0
ë A)ï{2,-5}ê B)ï{10,-2}êC)ï{4,5}êD) {-2,5}
#üêêê 2xì - 6x - 20 = 0
#êêêë2(xì - 3x - 10) = 0
êêêë2(x + 2)(x - 5) = 0
#êêêèx + 2 = 0 │ x - 5 = 0
#êêêë x = -2 │ x = 5
êêêêè {-2,5}
Ç D
7
#êêêïSolveï12aì + 7a - 10 = 0
êêêê2è 5
#ëA)ï{3,4}ê B)ï{ ─, ─ ─ }êC)ï{2,5}êD)ï{6,8}
êêêê3è 4
#üè12aì + 7a - 10 = 0ë ┌─>è 3a - 2 = 0 │ï4a + 5 = 0
#êï(3a - 2)(4a + 5) = 0ï──┘êè3a = 2 │ï4a = -5
#êêêêêêêï│
#êêêêêêê2 │êï5
#êêêêêêèa = ─ │èa = - ─
#êêêêêêê3 │êï4
Ç B
8
#êêêè Solveï4xì - 9 = 0
êè 3ï3êêêêêêè 2è 2
#èA)ï{ ─ ─, ─ }ëB)è{2,3}êC)ï{4,9}êD)ï{ ─, ─ ─ }
êè 2ï2êêêêêêè 3è 3
#üè4xì - 9 = 0êë ┌─>è 2x + 3 = 0 │ï2x - 3 = 0
#êï(2x + 3)(2x - 3) = 0ï──┘êï2x = -3 │ï2x = 3
#êêêêêêêï│
#êêêêêêê3 │ê3
#êêêêêê x = ─ ─ │èx = ─
#êêêêêêê2 │ê2
Ç A
9
#êêêïSolveï9xì - 30x + 25 = 0
êêêê 5
#è A)ï{3,5}êïB)è{ ─ }êïC)ï{-3,-5}êD)ï{9,5}
êêêê 3
#üè9xì - 30x + 25 = 0ë ┌─>è 3x - 5 = 0 │ï3x - 5 = 0
#êï(3x - 5)(3x - 5) = 0ï──┘êè3x = 5 │ï3x = 5
#êêêêêêêï│
#êêêêêêê5 │ê5
#êêêêêêèx = ─ │èx = ─
#êêêêêêê3 │ê3
Ç B
10
#êêêïSolveï42xì - 23x - 10 = 0
êè 2ï5êêêêêêë 2ï7
#è A)ï{─ ─, ─ }ë B)è{7,5}ê C)ï{6,12}ë D)ï{ ─, ─ }
êè 7ï6êêêêêêë 5ï3
#üï42xì - 23x - 10 = 0ë ┌─>è 7x + 2 = 0 │ï6x - 5 = 0
#ê (7x + 2)(6x - 5) = 0è──┘êï7x = -2 │ï6x = 5
#êêêêêêêï│
#êêêêêêê2 │ê5
#êêêêêê x = ─ ─ │èx = ─
#êêêêêêê7 │ê6
Ç A