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CHAPTER3.3T
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à 3.3ïSolving first degree equations.
äïPlease solve the following equations.
âêêê2x - 5 = 7
êêêê2x - 5 + 5 = 7 + 5
êêêê2x + 0 = 12
êêêê2x = 12
êêêê1ê 1
êêêê─∙(2x) = ─∙12,è x = 6
êêêê2ê 2
éS
To solve an equation such as, 3x + 4 = 10, you should first combine any
like terms if necessary.ïThis should be followed by any needed
applications of the addition property.ïFinally apply the multiplication
property to get the solution.ïSince there are no like terms on either
side of, 3x + 4 = 10, you may begin by applying the addition principle.
êêêè3x + 4 + (-4) = 10 + (-4)
êêêè3x + 0 = 6
êêêè3x = 6
Next apply the multiplication property.
ë1ê 1ê ┌ 1ë┐è 1êë 1
ë─∙(3x) = ─∙6,ë│ ─ ∙ 3 │x = ─∙6,ë1x = ─∙6,ëx = 2
ë3ê 3ê └ 3ë┘è 3êë 3
1
êêêëSolveï4x - 6 = 10
êA)ï-4êïB)ï8ê C)ï4ê D)ïå of ç
üêê4x - 6 = 10
êêë 4x - 6 + 6 = 10 + 6
êêë 4x + 0 = 16
êêë 4x = 16
êêë 1êï1
êêë ─x∙(4x) = ─x∙16 ─────────────>ïx = 4
êêë 4êï4
Ç C
2
êêêïSolveï4z + 3 = -2(z + 5)
êè 4êê 13êè 12
êA)ï─êèB) - ──ë C) - ──ë D)ïå of ç
êè 9êêï6êè 13
üï4z + 3 = -2(z + 5)êè┌─>ï6z = -13
ê 4z + 3 = -2z -10êë│è 1ê 1
ê 4z + 2z + 3 = -2z + 2z -10ï│è ─∙(6z) = ─∙(-13)
ê 6z + 3 = 0 - 10êë │è 6ê 6
ê 6z + 3 = -10êêï│êè13
ê 6z + 3 - 3 = -10 - 3ê │è z = - ──
ê 6z + 0 = -13 ───────────────┘êè 6
Ç B
3
êêê Solveï3(2k + 4) = 4(2k - 3)
êA)ï12êïB) -6ê C)ï-18ë D)ïå of ç
üï3(2k + 4) = 4(2k - 3)êë ┌─>ï-2k = -24
ê 6k + 12 = 8k - 12êêè│è┌ï1 ┐ê ┌ï1 ┐
ê 6k + (-8k) + 12 = 8k + (-8k) - 12 │è│- ─ │(-2k) = │- ─ │(-24)
ê -2k + 12 = 0 - 12êêè│è└ï2 ┘ê └ï2 ┘
ê -2k + 12 = -12êêë │
ê -2k + 12 + (-12) = -12 + (-12)è │è k = 12
ê -2k + 0 = -24ï───────────────────┘
Ç A
4
êêê Solveï3(4x - 2) = 12x - 6
A)ï-6ë B)ïall real numbersè C)ïno solutionè D)ïå of ç
üêêë 3(4x - 2) = 12x - 6
êêêë12x - 6 = 12x - 6
êêêë12x + (-12x) - 6 = 12x + (-12x) - 6
êêêë0 - 6 = 0 - 6
êêêë-6 = -6
êêêësolution is all real numbers
Ç B
5
êêèSolveï7(3y - 1) - 4 = 8(2y - 3) - 12
êA)ï15êïB) -5ê C)ï-20ë D)ïå of ç
üï7(3y - 1) - 4 = 8(2y - 3) - 12è ┌─>ï5y = -25
ê 21y - 7 - 4 = 16y - 24 - 12ê│è ┌ 1 ┐ê┌ 1 ┐
ê 21y - 11 = 16y - 36êê │è │ ─ │(5y) = │ ─ │(-25)
ê 21y +(-16y)-11 = 16y+(-16y) -36è│è └ 5 ┘ê└ 5 ┘
ê 5y - 11 = 0 - 36êêè │
ê 5y - 11 + 11 = -36 + 11êè │è y = -5
ê 5y + 0 = -25è───────────────────┘
Ç B
6
êêë Solveï5(3x - 4) - 2(x + 1) = 25
êêêë2êë47
êA)ï2êèB)ï─ê C)ï──êD)ïå of ç
êêêë3êë13
üï5(3x - 4) - 2(x + 1) = 25
ê 15x - 20 - 2x - 2 = 25êë┌─>ï┌ï1 ┐ê ┌ï1 ┐
ê (15x - 2x) + (-20 - 2) = 25ê│è │ ── │(13x) = │ ── │(47)
ê 13x + (-22) = 25êêè │è └ 13 ┘ê └ 13 ┘
ê 13x + (-22) + 22 = 25 + 22ê │ê 47
ê 13x + 0 = 47êêê │è x = ──
ê 13x = 47 ─────────────────────────┘ê 13
Ç C
äïPlease translate the following written phrases into
symbolic expressions.
â
êêêTwice a number added to nine.
êêêêè 2x + 9
éS
Remember that expressions such as decreased by, times, and the sum of
indicate subtraction, multiplication, and addition respectively.
7
êêë Translate two-thirds of a number.
êè 2êê1êê2
êA)ï─∙xêïB) ─∙xê C)ï─∙4ë D)ïå of ç
êè 3êê3êê3
ü
êêêêë 2
êêêêë ─∙x
êêêêë 3
Ç A
8
êëTranslate the sum of one-half a number and eleven.
êïx + 11êè1êêë11
ëA)ï──────ë B)ï─x + 11ëC)ïx + ──ëD)ïå of ç
êè 2êë 2êêë 2
ü
êêêêè 1
êêêêè ─∙x + 11
êêêêè 2
Ç B
9
êèTranslate four times the quotient of a number and three.
êêêë ┌ 3 ┐êè ┌ x ┐
ëA)ï4x + 3ë B)ï4∙│ ─ │ëC)ï4∙│ ─ │è D)ïå of ç
êêêë └ x ┘êè └ 3 ┘
ü
êêêêë┌ x ┐
êêêêè4∙│ ─ │
êêêêë└ 3 ┘
Ç C