Article Contents
- Equations with Fractions
- Unknown in the Numerator
- Unknown in the Denominator
- Clearing Fractions Early
- Examples
1. Equations with Fractions {#equations-with-fractions}
Fractions in equations can look scary, but the same balance principle applies.
Example with Fractions
3x+5=12
2. Unknown in the Numerator {#unknown-in-the-numerator}
This is the standard case: ax=b
Formula: Multiply both sides by
a
Example
Solve: 4x=7
Step 1: Multiply both sides by 4
4x×4=7×4
Step 2: Calculate
x=28
Step 3: Check
428=7✓
3. Unknown in the Denominator {#unknown-in-the-denominator}
When x is in the denominator, we need to be careful.
Example
Solve: x6=2
Step 1: Multiply both sides by
x
x6×x=2×x
6=2x
Step 2: Divide both sides by 2
x=3
Step 3: Check (remember: never divide by zero!)
36=2✓
Important: x=0 since we can't divide by zero!
4. Clearing Fractions Early {#clearing-fractions-early}
A helpful technique is to multiply the entire equation by the denominator to avoid working with fractions.
Example
Solve: 3x+2=5
Method 1: Direct approach
3x+2=5⇒x+2=15⇒x=13
Method 2: Clear fractions first
3x+2=5⇒(x+2)=5×3=15⇒x=13
Both methods work! Method 2 is often cleaner.
5. Examples {#examples}
Example 1: Unknown in Numerator
Solve: 32x=8
Step 1: Multiply both sides by 3
2x = 24
Step 2: Divide both sides by 2
x = 12
Check: 32×12=324=8✓
Example 2: Unknown in Denominator
Solve: x12=4
Step 1: Multiply both sides by x
12 = 4x
Step 2: Divide both sides by 4
x = 3
Check: 312=4✓
Example 3: Complex Fractions
Solve: 2x+5=7
Step 1: Multiply both sides by 2
x + 5 = 14
Step 2: Subtract 5 from both sides
x = 9
Check: 29+5=214=7✓
Summary
| Situation | Method |
| ax=b | Multiply both sides by a: x=ab |
| xa=b | Multiply both sides by x, then divide: x=a/b |
| bax=c | Multiply by b, then divide by a: x=bc/a |
Interactive Exercises
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