Solve the Linear Equation Involving a Fraction: -7x + 3 - 1/2 = 0

Linear Equations with Mixed Number Operations

Calculate the value of x:

7x+312=0 -7x+3-\frac{1}{2}=0

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:06 Let's find the value of X.
00:09 First, arrange the equation so that X is alone on one side.
00:21 Next, find a common denominator and multiply everything by it.
00:38 Now, collect all like terms together.
00:47 Isolate X by multiplying both sides by the reciprocal.
00:57 Remember, multiply numerator by numerator, and denominator by denominator.
01:02 And there you have it! That's how you solve for X.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Calculate the value of x:

7x+312=0 -7x+3-\frac{1}{2}=0

2

Step-by-step solution

To solve the equation 7x+312=0 -7x + 3 - \frac{1}{2} = 0 , follow these steps:

Step 1: Simplify the equation.
First, combine the constant terms 3 3 and 12 -\frac{1}{2} . Convert 3 3 to a fraction as 62 \frac{6}{2} to facilitate subtraction. Thus, 312=6212=52 3 - \frac{1}{2} = \frac{6}{2} - \frac{1}{2} = \frac{5}{2} .
The equation now becomes: 7x+52=0 -7x + \frac{5}{2} = 0 .

Step 2: Move the constant term to the other side.
Subtract 52\frac{5}{2} from both sides:
7x+5252=052 -7x + \frac{5}{2} - \frac{5}{2} = 0 - \frac{5}{2} .
This simplifies to: 7x=52 -7x = -\frac{5}{2} .

Step 3: Isolate x x .
Divide both sides by 7-7 to solve for x x :
x=527 x = \frac{-\frac{5}{2}}{-7} .
Simplify the expression:
x=514 x = \frac{5}{14} .

Thus, the solution to the equation is 514\boxed{\frac{5}{14}}, which corresponds to choice 3.

3

Final Answer

514 \frac{5}{14}

Key Points to Remember

Essential concepts to master this topic
  • Simplification: Combine constant terms before isolating the variable
  • Technique: Convert 3 to 62 \frac{6}{2} so 312=52 3 - \frac{1}{2} = \frac{5}{2}
  • Check: Substitute x=514 x = \frac{5}{14} : 7(514)+312=0 -7(\frac{5}{14}) + 3 - \frac{1}{2} = 0

Common Mistakes

Avoid these frequent errors
  • Adding fractions with different denominators incorrectly
    Don't add 3 - 1/2 = 2.5 using decimals = wrong simplified equation! This creates calculation errors and messy arithmetic. Always convert whole numbers to fractions with common denominators first.

Practice Quiz

Test your knowledge with interactive questions

\( x+x=8 \)

FAQ

Everything you need to know about this question

Why do I need to convert 3 to a fraction?

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Converting 3 to 62 \frac{6}{2} gives you a common denominator with 12 \frac{1}{2} . This makes subtraction much easier: 6212=52 \frac{6}{2} - \frac{1}{2} = \frac{5}{2} !

Can I use decimals instead of fractions?

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You could convert 12 \frac{1}{2} to 0.5, but keeping everything as fractions usually gives you exact answers without rounding errors. Fractions are more precise!

How do I divide by a negative number?

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When dividing both sides by -7, remember that dividing by a negative flips the sign. So 527 \frac{-\frac{5}{2}}{-7} becomes positive: 514 \frac{5}{14} .

What if I get confused with all the fractions?

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Take it step by step! First combine constants, then isolate the variable term, finally divide. Write each step clearly and double-check your fraction arithmetic.

Is there a faster way to solve this?

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You could multiply the entire equation by 2 first to clear the fraction: 2(7x+312)=2(0) 2(-7x + 3 - \frac{1}{2}) = 2(0) gives 14x+61=0 -14x + 6 - 1 = 0 , then solve normally.

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