Lesson 4: Write and Represent Inequalities6.AT.9

I can…

I can write inequalities to represent real-world situations.

Key words

• Write Inequalities — Represent a range of possible values with <, >, ≤, or ≥.
• Inequality — A math sentence that compares two sides with <, >, ≤, or ≥.
• Greater than — The > sign, showing one number is bigger.
• Less than — The < sign, showing one number is smaller.
• At least / At most — 'At least' means ≥. 'At most' means ≤.
• Variable — A letter that stands for a number that is unknown or can change.
• No more than — A phrase meaning less than or equal to (≤).
• Constraint — A limit that a solution must satisfy.
• Solution set — All the values that make an inequality true.

Steps

1. Clue: 'The suspect is at least 18 years old.'
2. I let a stand for the age. 'At least 18' means 18 or more.
3. 'At least' includes 18, so I use the symbol ≥.
4. My inequality is a ≥ 18. So a could be 18, 19, 20, and up.

Try it

Which inequality represents: 'A number t is at most 20'?

Check your answer

t ≤ 20

'At most 20' means 20 or less, so t ≤ 20.

Sentence starter

I know ___ because ___.

Goal: I can explain my inequality using the words inequality, greater than, less than, and at least / at most.