Simplify 2/5x + 4/3y + 7/9x + 3/4y: Combining Like Terms with Fractions

Combining Like Terms with Fractional Coefficients

25x+43y+79x+34y=? \frac{2}{5}x+\frac{4}{3}y+\frac{7}{9}x+\frac{3}{4}y=\text{?}

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the expression
00:05 Mark the appropriate variables
00:12 Use the commutative law and arrange the appropriate variables together
00:32 Multiply each fraction by the denominator of the second fraction to find the common denominator
00:35 Make sure to multiply both numerator and denominator
01:11 Collect terms, add with common denominator
01:22 Calculate the sums
01:33 Convert to mixed fraction
01:42 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

25x+43y+79x+34y=? \frac{2}{5}x+\frac{4}{3}y+\frac{7}{9}x+\frac{3}{4}y=\text{?}

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the given expression and separate like terms.
  • Step 2: Find a common denominator for terms with same variables.
  • Step 3: Add the fractions for each group of like terms.
  • Step 4: Simplify the expression to find the final result.

Now, let's work through each step:
Step 1: The expression is 25x+43y+79x+34y\frac{2}{5}x + \frac{4}{3}y + \frac{7}{9}x + \frac{3}{4}y. Group like terms together:
(25x+79x)+(43y+34y)(\frac{2}{5}x + \frac{7}{9}x) + (\frac{4}{3}y + \frac{3}{4}y).

Step 2: For (25x+79x)(\frac{2}{5}x + \frac{7}{9}x), find a common denominator for the fractions 2/52/5 and 7/97/9, which is 45.
Convert 25\frac{2}{5} to 1845\frac{18}{45} and 79\frac{7}{9} to 3545\frac{35}{45}.

Step 3: Add the fractions for xx:
1845x+3545x=5345x\frac{18}{45}x + \frac{35}{45}x = \frac{53}{45}x.

For (43y+34y)(\frac{4}{3}y + \frac{3}{4}y), find a common denominator, which is 12.
Convert 43\frac{4}{3} to 1612\frac{16}{12} and 34\frac{3}{4} to 912\frac{9}{12}.

Add the fractions for yy:
1612y+912y=2512y\frac{16}{12}y + \frac{9}{12}y = \frac{25}{12}y.

Step 4: Combine results to express the simplified form:
5345x+2512y\frac{53}{45}x + \frac{25}{12}y.

As mixed numbers, the solution becomes:
1845x+2112y1\frac{8}{45}x + 2\frac{1}{12}y.

Therefore, the solution to the problem is 1845x+2112y1\frac{8}{45}x + 2\frac{1}{12}y.

3

Final Answer

1845x+2112y 1\frac{8}{45}x+2\frac{1}{12}y

Key Points to Remember

Essential concepts to master this topic
  • Like Terms: Variables with same letter can be combined together
  • Common Denominators: Convert 25 \frac{2}{5} to 1845 \frac{18}{45} when LCD is 45
  • Check: Count terms before and after: 4 terms become 2 terms ✓

Common Mistakes

Avoid these frequent errors
  • Adding coefficients without finding common denominators
    Don't add 25+79=914 \frac{2}{5} + \frac{7}{9} = \frac{9}{14} ! This ignores different denominators and gives completely wrong results. Always find the LCD first, then convert both fractions before adding.

Practice Quiz

Test your knowledge with interactive questions

\( 3x+4x+7+2=\text{?} \)

FAQ

Everything you need to know about this question

Why can't I just add the numerators and denominators separately?

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Because fractions represent parts of different wholes! Adding 25+79 \frac{2}{5} + \frac{7}{9} means adding 2 fifths plus 7 ninths - you need a common denominator to combine them properly.

How do I find the LCD of 5 and 9?

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List multiples of each number: 5, 10, 15, 20, 25, 30, 35, 40, 45... and 9, 18, 27, 36, 45... The first number that appears in both lists is your LCD!

What if the fractions don't simplify nicely?

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That's okay! Sometimes answers like 5345 \frac{53}{45} can't be simplified further. You can leave it as an improper fraction or convert to a mixed number like 1845 1\frac{8}{45} .

Do I have to convert to mixed numbers?

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Not necessarily! Both 5345x \frac{53}{45}x and 1845x 1\frac{8}{45}x are correct. Mixed numbers are often easier to understand, but improper fractions work fine too.

Can I combine the x and y terms together?

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No! Terms with different variables are not like terms. You cannot combine 5345x \frac{53}{45}x and 2512y \frac{25}{12}y - they must stay separate in your final answer.

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