Lesson 7 of 15
Putting two expressions together
Show on a big screenTwo classes bring books to a stall. One brings 3n + 4 crates. The other brings 2n + 5. Can the two amounts be written as one expression?
3n, 4, 2n, 5. Step 1 of 4
- Write every term in one row:
3n,4,2n,5. - Collect the
n-terms:5n. - Collect the plain numbers:
9. - Total =
5n + 9.
Yes. Together they bring 5n + 9 crates.
Rule: add two expressions by writing every term in one row. Then collect like terms.
Taking away is harder. A bracket is the ( ) round some terms. The minus takes away every term inside the bracket. So (5n + 3) − (2n + 1) is 5n + 3 − 2n − 1. That collects to 3n + 2.
Pick a job. Slide n. Compare the long form with the tidy form.
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Try the lab to finish this lesson.