Solve for X: -3(1/2x + 4) = 1/2 Linear Equation Solution

Linear Equations with Distributive Property

Solve for x:

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

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:06 Let's find the unknown value of X together.
00:10 First, open the parentheses properly and multiply each term inside.
00:21 Next, multiply everything by 2 to get rid of any fractions.
00:36 Now, arrange the equation so that X is all by itself on one side.
00:44 Time to collect like terms.
00:48 Then, isolate X to find its value.
00:56 And just like that, we've solved the problem for X!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for x:

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

2

Step-by-step solution

We open the parentheses on the left side by the distributive property and use the formula:

a(x+b)=ax+ab a(x+b)=ax+ab

32x12=12 -\frac{3}{2}x-12=\frac{1}{2}

We multiply all terms by 2 to get rid of the fractions:

3x12×2=1 -3x-12\times2=1

3x24=1 -3x-24=1

We will move the minus 24 to the right section and keep the corresponding sign:

3x=24+1 -3x=24+1

3x=25 -3x=25

Divide both sections by minus 3:

3x3=253 \frac{-3x}{-3}=\frac{25}{-3}

x=253 x=-\frac{25}{3}

3

Final Answer

253 -\frac{25}{3}

Key Points to Remember

Essential concepts to master this topic
  • Distributive Rule: Multiply -3 by each term inside parentheses first
  • Technique: Clear fractions by multiplying all terms by 2: 3x24=1 -3x - 24 = 1
  • Check: Substitute x=253 x = -\frac{25}{3} back into original equation to verify ✓

Common Mistakes

Avoid these frequent errors
  • Not distributing negative sign correctly
    Don't forget the negative sign when distributing: -3(1/2x + 4) = -3/2x - 12, not -3/2x + 12! Missing the negative creates a completely wrong equation. Always distribute the negative sign to every term inside parentheses.

Practice Quiz

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\( 5x=1 \)

What is the value of x?

FAQ

Everything you need to know about this question

Why do I multiply by 2 to clear fractions?

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Multiplying by 2 eliminates all denominators of 2 in one step! This turns 32x12=12 -\frac{3}{2}x - 12 = \frac{1}{2} into the simpler 3x24=1 -3x - 24 = 1 .

What if I distribute incorrectly?

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Double-check each term! Remember: 3×12x=32x -3 \times \frac{1}{2}x = -\frac{3}{2}x and 3×4=12 -3 \times 4 = -12 . The negative sign affects everything.

How do I handle the negative fraction answer?

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Negative fractions are normal! 253 -\frac{25}{3} means the same as 253 \frac{-25}{3} . Keep it as an improper fraction unless asked to convert.

Can I solve this without clearing fractions first?

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Yes, but it's much harder! You'd work with fractions throughout. Clearing fractions first makes the arithmetic much simpler and reduces calculation errors.

How do I verify my negative answer is correct?

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Substitute x=253 x = -\frac{25}{3} into the original equation. If 3(12(253)+4)=12 -3(\frac{1}{2} \cdot (-\frac{25}{3}) + 4) = \frac{1}{2} , you're right!

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