Lesson 4: Write and Represent Inequalities6.AT.9

I can…

I can write inequalities to represent real-world situations.

Key words

• Write Inequalities — Use <, >, ≤, or ≥ to show many numbers.
• Inequality — A math sentence that compares sides with <, >, ≤, or ≥.
• Greater than — The > sign. It shows one number is bigger.
• Less than — The < sign. It shows one number is smaller.
• At least / At most — ≥ means that amount or more. ≤ means that amount or less.
• Variable — A letter that stands for a number.
• No more than — This much or less. It is the same as ≤.
• Constraint — A rule an answer must follow.
• Solution set — All the values that make the sentence 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.