12 multiple-choice questions, progressively harder.
Solve x2+32=4\dfrac{x}{2} + \dfrac{3}{2} = 42x+23=4 for xxx.
Solution
Correct answer: A
Subtract the constant 32\frac{3}{2}23 from both sides, then multiply by the divisor 222.
x2=4−32=82−32=52\frac{x}{2} = 4 - \frac{3}{2} = \frac{8}{2} - \frac{3}{2} = \frac{5}{2}2x=4−23=28−23=25
Multiplying by 222 gives x=5x = 5x=5. Check: 52+32=82=4\frac{5}{2} + \frac{3}{2} = \frac{8}{2} = 425+23=28=4, which is true.
Solve 8x−5=118x - 5 = 118x−5=11 for xxx.
Correct answer: B
Add 555 to both sides, then divide by 888.
8x−5+5=11+5 ⇒ 8x=168x - 5 + 5 = 11 + 5 \;\Rightarrow\; 8x = 168x−5+5=11+5⇒8x=16
Dividing by 888 gives x=2x = 2x=2. Check: 8(2)−5=16−5=118(2) - 5 = 16 - 5 = 118(2)−5=16−5=11, which is true.
Solve 4(x+1)=24(x + 1) = 24(x+1)=2 for xxx.
Correct answer: C
Distribute the 444 across both terms inside the parentheses, then solve.
4(x+1)=4x+4=2 ⇒ 4x=−2 ⇒ x=−24=−124(x + 1) = 4x + 4 = 2 \;\Rightarrow\; 4x = -2 \;\Rightarrow\; x = -\frac{2}{4} = -\frac{1}{2}4(x+1)=4x+4=2⇒4x=−2⇒x=−42=−21
Check in the original: 4(−12+1)=4⋅12=24\left(-\frac{1}{2} + 1\right) = 4 \cdot \frac{1}{2} = 24(−21+1)=4⋅21=2, which is true.
Solve 2x−0.5=3.52x - 0.5 = 3.52x−0.5=3.5 for xxx.
Add the decimal constant 0.50.50.5 to both sides, then divide by 222.
2x−0.5+0.5=3.5+0.5 ⇒ 2x=42x - 0.5 + 0.5 = 3.5 + 0.5 \;\Rightarrow\; 2x = 42x−0.5+0.5=3.5+0.5⇒2x=4
Dividing by 222 gives x=2x = 2x=2. Check: 2(2)−0.5=4−0.5=3.52(2) - 0.5 = 4 - 0.5 = 3.52(2)−0.5=4−0.5=3.5, which is true.
Solve 6x+1.4=56x + 1.4 = 56x+1.4=5 for xxx.
Subtract the decimal constant 1.41.41.4 from both sides, then divide by 666.
6x+1.4−1.4=5−1.4 ⇒ 6x=3.66x + 1.4 - 1.4 = 5 - 1.4 \;\Rightarrow\; 6x = 3.66x+1.4−1.4=5−1.4⇒6x=3.6
Dividing by 666 gives x=0.6x = 0.6x=0.6. Check: 6(0.6)+1.4=3.6+1.4=56(0.6) + 1.4 = 3.6 + 1.4 = 56(0.6)+1.4=3.6+1.4=5, which is true.
Solve 14=6x+214 = 6x + 214=6x+2 for xxx.
The variable term is on the right; subtract the constant 222 from both sides, then divide by 666.
14−2=6x+2−2 ⇒ 12=6x14 - 2 = 6x + 2 - 2 \;\Rightarrow\; 12 = 6x14−2=6x+2−2⇒12=6x
Dividing by 666 gives x=2x = 2x=2. Check: 6(2)+2=12+2=146(2) + 2 = 12 + 2 = 146(2)+2=12+2=14, which is true.
Solve 5x−3x+7=15x - 3x + 7 = 15x−3x+7=1 for xxx.
Correct answer: D
Combine the like terms 5x−3x=2x5x - 3x = 2x5x−3x=2x first, then solve the two-step equation.
2x+7=1 ⇒ 2x=−6 ⇒ x=−32x + 7 = 1 \;\Rightarrow\; 2x = -6 \;\Rightarrow\; x = -32x+7=1⇒2x=−6⇒x=−3
Check in the original: 5(−3)−3(−3)+7=−15+9+7=15(-3) - 3(-3) + 7 = -15 + 9 + 7 = 15(−3)−3(−3)+7=−15+9+7=1, which is true.
Solve 12x+3=8\tfrac{1}{2}x + 3 = 821x+3=8 for xxx.
Subtract the constant 333 from both sides, leaving 12x=5\frac{1}{2}x = 521x=5. Dividing by 12\frac{1}{2}21 is the same as multiplying by 222.
x=5⋅2=10x = 5 \cdot 2 = 10x=5⋅2=10
Check: 12(10)+3=5+3=8\frac{1}{2}(10) + 3 = 5 + 3 = 821(10)+3=5+3=8, which is true.
Solve 34x−2=7\tfrac{3}{4}x - 2 = 743x−2=7 for xxx.
Add the constant 222 to both sides, leaving 34x=9\frac{3}{4}x = 943x=9. Then divide by 34\frac{3}{4}43, which means multiply by the reciprocal 43\frac{4}{3}34.
x=9⋅43=363=12x = 9 \cdot \frac{4}{3} = \frac{36}{3} = 12x=9⋅34=336=12
Check: 34(12)−2=9−2=7\frac{3}{4}(12) - 2 = 9 - 2 = 743(12)−2=9−2=7, which is true.
You solve x2+4=9\dfrac{x}{2} + 4 = 92x+4=9 and get x=10x = 10x=10. To check, what does the left side x2+4\dfrac{x}{2} + 42x+4 become?
Substitute 101010 for xxx in the original left side, dividing before adding.
102+4=5+4=9\frac{10}{2} + 4 = 5 + 4 = 9210+4=5+4=9
The left side equals 999, the same as the right side, so the solution checks out.
After distributing in 3(x−4)=93(x - 4) = 93(x−4)=9, which equation do you solve next?
Distributing multiplies the 333 by every term inside the parentheses, both the xxx and the −4-4−4.
3(x−4)=3⋅x−3⋅4=3x−123(x - 4) = 3 \cdot x - 3 \cdot 4 = 3x - 123(x−4)=3⋅x−3⋅4=3x−12
So the next equation is 3x−12=93x - 12 = 93x−12=9. From there, add 121212 and divide by 333 to get x=7x = 7x=7.
Solve −x3+5=2-\dfrac{x}{3} + 5 = 2−3x+5=2 for xxx.
Subtract the constant 555 from both sides, leaving −x3=−3-\frac{x}{3} = -3−3x=−3. Multiply both sides by −3-3−3 to undo the division by 333 and the negative sign together.
−3⋅(−x3)=−3⋅(−3) ⇒ x=9-3 \cdot \left(-\frac{x}{3}\right) = -3 \cdot (-3) \;\Rightarrow\; x = 9−3⋅(−3x)=−3⋅(−3)⇒x=9
Check: −93+5=−3+5=2-\frac{9}{3} + 5 = -3 + 5 = 2−39+5=−3+5=2, which is true.
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