Solve the Equation: Unraveling 7a(3 + 1/a) - 2a = 0

Linear Equations with Variable Distribution

Solve for a:

7a(3+1a)2a=0 7a(3+\frac{1}{a})-2a=0

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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
00:20 Simplify what we can
00:27 Collect like terms
00:32 Arrange the equation so that one side has only the unknown A
00:40 Isolate A
00:47 And 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

Solve for a:

7a(3+1a)2a=0 7a(3+\frac{1}{a})-2a=0

2

Step-by-step solution

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

  • Step 1: Distribute and Simplify

    Begin by distributing the 7a 7a across the terms inside the parentheses:

    7a(3+1a)=7a×3+7a×1a 7a(3+\frac{1}{a}) = 7a \times 3 + 7a \times \frac{1}{a}

    This simplifies to:

    21a+7 21a + 7

    Thus, the equation becomes:

    21a+72a=0 21a + 7 - 2a = 0

  • Step 2: Combine Like Terms

    Combine the 'a' terms on the left side:

    21a2a+7=0 21a - 2a + 7 = 0

    This simplifies to:

    19a+7=0 19a + 7 = 0

  • Step 3: Solve for a a

    Rearrange the equation to solve for a a :

    19a=7 19a = -7

    Divide both sides by 19 to isolate a a :

    a=719 a = -\frac{7}{19}

Therefore, the solution to the equation is a=719 a = -\frac{7}{19} .

3

Final Answer

a=719 a=-\frac{7}{19}

Key Points to Remember

Essential concepts to master this topic
  • Distribution Rule: Multiply each term inside parentheses by the outside factor
  • Technique: 7a×1a=7 7a \times \frac{1}{a} = 7 because variables cancel out
  • Check: Substitute a=719 a = -\frac{7}{19} back: 19(719)+7=0 19(-\frac{7}{19}) + 7 = 0

Common Mistakes

Avoid these frequent errors
  • Incorrectly simplifying the fraction term
    Don't calculate 7a×1a=7aa=71 7a \times \frac{1}{a} = \frac{7a}{a} = \frac{7}{1} without canceling properly = wrong distribution! Students often forget that aa=1 \frac{a}{a} = 1 when a0 a \neq 0 . Always cancel matching variables in numerator and denominator to get 7a×1a=7 7a \times \frac{1}{a} = 7 .

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 does 7a×1a 7a \times \frac{1}{a} equal 7 and not 7aa \frac{7a}{a} ?

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Great question! When you multiply 7a×1a 7a \times \frac{1}{a} , you can rewrite it as 7aa \frac{7a}{a} . Since a appears in both numerator and denominator, they cancel out (as long as a0 a \neq 0 ), leaving you with just 7.

What if I get confused with the distribution step?

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Break it down piece by piece! 7a(3+1a) 7a(3 + \frac{1}{a}) means multiply 7a by each term inside. So you get 7a×3=21a 7a \times 3 = 21a and 7a×1a=7 7a \times \frac{1}{a} = 7 . Then add them: 21a+7 21a + 7 .

How do I know when variables cancel out?

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Variables cancel when you have the same variable in both numerator and denominator. For example, aa=1 \frac{a}{a} = 1 , 3xx=3 \frac{3x}{x} = 3 , or 5y2y=5y \frac{5y^2}{y} = 5y . Just remember the variable can't equal zero!

Why do we combine like terms after distribution?

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After distributing, you often get multiple terms with the same variable. Combining like terms simplifies the equation and makes it easier to solve. In this problem, 21a2a=19a 21a - 2a = 19a gives us a simpler equation to work with.

Can this equation have no solution or infinite solutions?

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For this type of linear equation, we typically get exactly one solution. No solution occurs when you get something like 0=5 0 = 5 (impossible). Infinite solutions happen when you get 0=0 0 = 0 (always true).

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