Grade 6 · Maths · Lessons
Two ways to write the same thing
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Two ways to write the same thing.The big ideaThe same number can be written two ways. Test a number to be sure.
How it works
The same number can be written two ways. Test a number to be sure.
Add like terms: 2x + x + 3x + x = 7x.
Check with a number: 5(2y + 5) is 10y + 25, not 10y + 5.
Example 1: Like terms
- 2x + x + 3x + x.
- Add the coefficients: 2 + 1 + 3 + 1 = 7.
- It is 7x.
Example 2: Another
- y + 3y + y + 2y.
- 1 + 3 + 1 + 2 = 7.
- It is 7y.
Example 3: Test it
- Is 5(2y + 5) the same as 10y + 5?
- Try y = 1: 5 × 7 = 35 but 10 + 5 = 15.
- They are different, so the answer is no.
Words to know
- like terms
- Terms with the same variable.
- equivalent expressions
- Expressions that always give the same number.
Watch out
- A letter on its own has coefficient 1.
- Multiply every term in the brackets.
- Test a number to check.
Try it
- Simplify: 3a + 2a
- Simplify: 4b + b
- Are 2(x + 3) and 2x + 6 the same?
- Are 3(y + 2) and 3y + 2 the same?
Answers: 1. 5a · 2. 5b · 3. yes · 4. no
For grown-upsTest two expressions with a number to see whether they match.