Solve for X in 7(x+5)-3(x-2)=5: Linear Equation Practice

Linear Equations with Distributive Property

Solve for X:

7(x+5)3(x2)=5 7(x+5)-3(x-2)=5

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:03 Carefully open parentheses properly, multiply by each factor
00:27 Solve each multiplication separately
00:35 Negative times negative always equals positive
00:43 Collect like terms
00:50 Arrange the equation so that X is isolated on one side
01:02 Collect like terms
01:08 Isolate X
01:14 Simplify as much as possible
01:18 This is the solution to the problem

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve for X:

7(x+5)3(x2)=5 7(x+5)-3(x-2)=5

2

Step-by-step solution

To solve the given equation 7(x+5)3(x2)=5 7(x + 5) - 3(x - 2) = 5 , we follow these steps:

  • Step 1: Apply the distributive property.
    Distribute 7 over (x+5) (x + 5) to obtain 7x+35 7x + 35 .
    Distribute -3 over (x2) (x - 2) to obtain 3x+6 -3x + 6 .
    The equation becomes 7x+353x+6=5 7x + 35 - 3x + 6 = 5 .
  • Step 2: Combine like terms.
    Combine the x x terms 7x 7x and 3x -3x to get 4x 4x .
    Combine the constant terms 35 35 and 6 6 to get 41 41 .
    The equation simplifies to 4x+41=5 4x + 41 = 5 .
  • Step 3: Isolate the variable x x .
    Subtract 41 from both sides: 4x+4141=541 4x + 41 - 41 = 5 - 41 .
    This simplifies to 4x=36 4x = -36 .
    Divide both sides by 4 to solve for x x : x=364 x = \frac{-36}{4} .
    The solution is x=9 x = -9 .

Therefore, the solution to the equation is x=9 x = -9 .

3

Final Answer

9 -9

Key Points to Remember

Essential concepts to master this topic
  • Rule: Apply distributive property before combining like terms
  • Technique: Distribute: 7(x+5) = 7x + 35 and -3(x-2) = -3x + 6
  • Check: Substitute x = -9: 7(-9+5) - 3(-9-2) = 7(-4) - 3(-11) = -28 + 33 = 5 ✓

Common Mistakes

Avoid these frequent errors
  • Combining terms before distributing
    Don't try to combine 7(x+5) and -3(x-2) directly = impossible to simplify! You must distribute first to remove parentheses. Always distribute multiplication over addition/subtraction before combining like terms.

Practice Quiz

Test your knowledge with interactive questions

Solve for X:

\( x - 3 + 5 = 8 - 2 \)

FAQ

Everything you need to know about this question

Why can't I just combine the coefficients 7 and -3 first?

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The coefficients 7 and -3 are multiplying different expressions in parentheses. You must distribute each coefficient to its terms first, then combine like terms afterward.

How do I handle the negative sign in front of 3(x-2)?

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The negative sign belongs to the 3, making it -3. When you distribute: -3(x-2) = -3x + 6. Remember that negative times negative equals positive!

What if I make an error while distributing?

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Double-check each distribution separately! For 7(x+5): multiply 7×x and 7×5. For -3(x-2): multiply -3×x and -3×(-2). Take your time with the signs.

How do I know when to stop simplifying?

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Stop when you have x = [number]. If you still have terms with x on both sides, or x has a coefficient other than 1, keep simplifying until x stands alone.

Can I check my work before finishing?

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Yes! After each step, make sure both sides still equal each other. The final check is substituting your answer back into the original equation to verify it works.

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