Positive and Negative Numbers Slideshow 2, Mr Richard Sasaki

Objectives Recall how inequalities relate to the number line Understand the meaning of positive and negative numbers Understanding how to use inequalities for positive and negative numbers 4 minute inequality drill! Please place inequality symbols in the right place.

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The Number Line Let’s have another look at a number line…(well a line). 𝑥 𝑦 Which number is greater, 𝑥 or 𝑦? 𝑦 is greater than 𝑥. 𝑦 > 𝑥 We know this is true, even if no numbers are shown. (Greater numbers are always on the right of the number line.)

The Number Line Let’s have a look at a number line. This time there is one number! −∞ ∞ 𝑦 𝑥 What can we say about 𝑥? 𝑥 > What can we say about 𝑦? 𝑦 < So 𝑦 is and negative 𝑥 is . positive

Positive and Negative Numbers Numbers greater than 0 are called numbers and numbers less than 0 are called numbers. positive negative −∞ ∞ Negative numbers Positive numbers The number 0 is not positive or negative (disputed, the French believe it is both). However, 0.00000001 would be positive and −0.00000001 would be negative.

Positive and Negative Numbers −∞ ∞ −7 −2 By looking at the number line, it is very easy to see which numbers are greater (or less) than other numbers. Which is greater? −2 is greater. As −2 is further to the right, −2 > −7.

Example C B D A -∞ ∞ Find which numbers A, B, C and D represent. A is . 2 Complete each of the statements below with an inequality symbol. B is . −4 C is . −5½ (Or − 11 2 ) A D > C B < D is . −½ D B >

−10 10 positive negative positive negative positive neither/both 9 2 − 1 2 1 −4 𝑎 𝑎>𝑑 or 𝑑<𝑎 −2 − 1 2 1 5 2 4

9 2 8.5 − 1 2 3 2 29 3 −7.5 > > > > < < > > > 4 is greater than −2 − 1 2 is less than 1 2 − 2 3 − 1 2 1 3 − 2 3 <− 1 2 < 1 3 𝑥= 1 2 , 𝑦=− 5 6 1 2 + 5 6 = 3 6 + 5 6 = 4 3