Solve (1/2x+3)-(4x+7)=1: Linear Equation with Fractions

Linear Equations with Distribution and Fractions

(12x+3)(4x+7)=1 (\frac{1}{2}x+3)-(4x+7)=1

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:03 Open parentheses properly, multiply by each factor
00:06 Negative times positive is always negative
00:12 Collect like terms
00:23 Arrange the equation so that X is isolated on one side
00:38 Isolate X
00:49 Convert from mixed number to fraction
00:52 Write division as multiplication by reciprocal
00:58 This is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

(12x+3)(4x+7)=1 (\frac{1}{2}x+3)-(4x+7)=1

2

Step-by-step solution

To solve the equation (12x+3)(4x+7)=1 (\frac{1}{2}x + 3) - (4x + 7) = 1 , follow these steps:

  • Simplify the Left Side:

Begin by distributing the negative sign to the terms in the parentheses on the left-hand side: (12x+3)4x7=1(\frac{1}{2}x + 3) - 4x - 7 = 1

Combine like terms: 12x4x+37=1\frac{1}{2}x - 4x + 3 - 7 = 1

This simplifies to: 72x4=1-\frac{7}{2}x - 4 = 1

  • Isolate the Variable xx:

Add 4 to both sides to isolate the term involving xx: 72x4+4=1+4-\frac{7}{2}x - 4 + 4 = 1 + 4

Resulting in: 72x=5-\frac{7}{2}x = 5

  • Solve for xx:

Multiply both sides by the reciprocal of 72-\frac{7}{2}, which is 27-\frac{2}{7}, to solve for xx: x=5×(27)x = 5 \times \left(-\frac{2}{7}\right)

Calculate the product: x=107x = -\frac{10}{7}

Convert to a mixed number: x=137x = -1\frac{3}{7}

Therefore, the solution to the problem is x=137 x = -1\frac{3}{7} .

The correct choice from the options given is choice 137 -1\frac{3}{7} (Choice 3).

3

Final Answer

137 -1\frac{3}{7}

Key Points to Remember

Essential concepts to master this topic
  • Distribution: Apply negative sign to both terms inside parentheses
  • Technique: Combine 12x4x=72x \frac{1}{2}x - 4x = -\frac{7}{2}x by finding common denominator
  • Check: Substitute x=137 x = -1\frac{3}{7} back into original equation ✓

Common Mistakes

Avoid these frequent errors
  • Incorrectly distributing the negative sign
    Don't forget to distribute the negative to both terms: -(4x + 7) = -4x - 7, not -4x + 7! Missing the negative on the 7 gives wrong answers. Always distribute the negative sign to every term inside the parentheses.

Practice Quiz

Test your knowledge with interactive questions

\( 5x=1 \)

What is the value of x?

FAQ

Everything you need to know about this question

Why do I need to distribute the negative sign to both terms?

+

The negative sign in front of parentheses means multiply everything inside by -1. So -(4x + 7) becomes (-1)(4x) + (-1)(7) = -4x - 7. Forgetting this creates wrong equations!

How do I subtract fractions with different denominators like 1/2x - 4x?

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Convert to the same denominator first! Since 4x = 82x \frac{8}{2}x , you get 12x82x=72x \frac{1}{2}x - \frac{8}{2}x = -\frac{7}{2}x . Always find a common denominator before combining.

What's the easiest way to solve -7/2x = 5?

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Multiply both sides by the reciprocal of 72 -\frac{7}{2} , which is 27 -\frac{2}{7} . This gives you x=5×(27)=107 x = 5 \times (-\frac{2}{7}) = -\frac{10}{7} .

How do I convert -10/7 to a mixed number?

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Divide: -10 ÷ 7 = -1 remainder -3. So 107=137 -\frac{10}{7} = -1\frac{3}{7} . The negative sign applies to the whole mixed number!

Should I check my answer in the original equation?

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Always! Substitute x=137 x = -1\frac{3}{7} back into (12x+3)(4x+7)=1 (\frac{1}{2}x+3)-(4x+7)=1 to verify both sides equal 1. This catches calculation errors.

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