Simplify and Solve: Combining Fractions and Decimals in 6 4/5x + 7 1/2x + 4 1/3x * 7.3x = ?

Algebraic Simplification with Mixed Numbers

645x+712x+413x7.3x=? 6\frac{4}{5}x+7\frac{1}{2}x+4\frac{1}{3}x\cdot7.3x=\text{?}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simply
00:06 We'll use the formula to convert a mixed fraction to a fraction
00:11 We'll use this formula in our exercise
00:38 We'll convert a decimal fraction to a fraction and substitute in the exercise
01:00 Let's calculate the numerators
01:23 Multiply each fraction by the second denominator to find the common denominator
01:33 When multiplying fractions, be sure to multiply numerator by numerator and denominator by denominator
01:43 Let's calculate the products
01:54 We'll use long multiplication to calculate the product
02:00 Each time we'll multiply and substitute accordingly
02:40 Let's combine the fractions with the common denominator
03:07 Dividing by 10 is actually moving the decimal point one place
03:10 Let's substitute in our exercise
03:21 Let's break down 949 into 930 plus 19
03:31 Let's break down the fraction into a whole number and remainder
03:42 Let's convert the whole fraction to a whole number
03:50 Let's combine into a mixed fraction
03:56 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

645x+712x+413x7.3x=? 6\frac{4}{5}x+7\frac{1}{2}x+4\frac{1}{3}x\cdot7.3x=\text{?}

2

Step-by-step solution

To solve this problem, we need to follow a systematic approach:

  • Step 1: Convert all mixed numbers into improper fractions.
  • Step 2: Carry out the multiplication between the terms 413x7.3x 4\frac{1}{3}x \cdot 7.3x .
  • Step 3: Combine the terms by adding the coefficients of x x and x2 x^2 .

Let's proceed with these steps:
Step 1: Convert mixed numbers to improper fractions.
645x=(345)x 6\frac{4}{5}x = \left(\frac{34}{5}\right)x 712x=(152)x 7\frac{1}{2}x = \left(\frac{15}{2}\right)x 413=133 4\frac{1}{3} = \frac{13}{3} Step 2: Compute the multiplication and product.
(133)x7.3x=(1337.3)x2=(94.93)x2 \left(\frac{13}{3}\right)x \cdot 7.3x = \left(\frac{13}{3} \cdot 7.3\right)x^2 = \left(\frac{94.9}{3}\right)x^2 Approximate 94.93=31.633... \frac{94.9}{3} = 31.633... or convert to a fraction 311930 31\frac{19}{30} .
Step 3: Combine all like terms by their variables.
(345)x+(152)x+311930x2 \left(\frac{34}{5}\right)x + \left(\frac{15}{2}\right)x + 31\frac{19}{30}x^2 Converting to decimal form: 6.8x+7.5x=14.3x 6.8x + 7.5x = 14.3x Thus, the final expression combines neatly as:
14.3x+311930x2 14.3x + 31\frac{19}{30}x^2

After reviewing the steps and calculations, the solution to the expression is 14.3x+311930x2 14.3x + 31\frac{19}{30}x^2 .

3

Final Answer

14.3x+311930x2 14.3x+31\frac{19}{30}x^2

Key Points to Remember

Essential concepts to master this topic
  • Order of Operations: Multiplication before addition for 413x7.3x 4\frac{1}{3}x \cdot 7.3x
  • Technique: Convert mixed numbers to improper fractions: 645=345 6\frac{4}{5} = \frac{34}{5}
  • Check: Verify by combining like terms separately: 14.3x + quadratic term ✓

Common Mistakes

Avoid these frequent errors
  • Adding all coefficients together
    Don't add 6.8 + 7.5 + 4.33 + 7.3 = 25.93x! This ignores that multiplication creates an x² term, not another x term. Always follow order of operations: multiply 413x7.3x 4\frac{1}{3}x \cdot 7.3x first to get 311930x2 31\frac{19}{30}x^2 , then add only the x terms together.

Practice Quiz

Test your knowledge with interactive questions

Are the expressions the same or not?

\( 20x \)

\( 2\times10x \)

FAQ

Everything you need to know about this question

Why do I multiply the x terms instead of adding them?

+

When you see 413x7.3x 4\frac{1}{3}x \cdot 7.3x , you're multiplying x times x, which gives you x2 x^2 ! The coefficients multiply too: 413×7.3 4\frac{1}{3} \times 7.3 .

How do I convert mixed numbers to work with decimals?

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You can either convert mixed numbers to improper fractions or decimals. For example, 645=6.8 6\frac{4}{5} = 6.8 and 712=7.5 7\frac{1}{2} = 7.5 . Choose whichever feels easier!

What's the difference between x and x² terms?

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x terms are linear (first degree) and x² terms are quadratic (second degree). You can only combine like terms, so 14.3x and 311930x2 31\frac{19}{30}x^2 stay separate!

Why is my final answer a mixed number and decimal?

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That's totally normal! The coefficient of x became a clean decimal (14.3), while the coefficient of x² stayed as a mixed number 311930 31\frac{19}{30} . Both forms are mathematically correct.

How do I check if this answer is right?

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Substitute a test value for x (like x = 1) into both the original expression and your final answer. If they give the same result, you're correct!

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