90 likes | 198 Views
Ch. 8 Integers. Understanding Rational Numbers. A rational number is any number that can be written as a quotient a/b, where a and b are integers and b is NOT equal to 0. Examples: 3 1/8, -0.28 and 5 are all rational numbers because they can be written as 25/8, -28/100, and 5/1.
E N D
Understanding Rational Numbers • A rational number is any number that can be written as a quotient a/b, where a and b are integers and b is NOT equal to 0. • Examples: 3 1/8, -0.28 and 5 are all rational numbers because they can be written as 25/8, -28/100, and 5/1.
Graph the rational numbers on the number line. 1) -1 3/8 2) 0.75 3) -7/8 4) -1/8
Adding Integers • IMPORTANT THINGS TO REMEMBER: • When adding two negative numbers the answer will always be negative. Ex. -5 + -7= -12 • If you are adding a positive and a negative number. Look to see which number is larger. The larger number’s sign (+, -) will decide if the answer will be positive or negative. Ex. 5+ -7 = 7 is the bigger number so the answer will be a negative number. Ex. -6 + 11= 11 is the bigger number so the answer will be a positive number.
Problems • -4 + -18 = • 17 + -29= • -4 + -5 = • -8+ -5 + 6= • -18+ 18= • -20+ 4= • -3+ 2+ 2=
Subtracting Integers • IMPORTANT THINGS TO REMEMBER! • When subtracting two positive numbers look at the 1st number. If it is less than the second number the answer will be negative. Ex. 10-12= -2 • When you are subtracting a negative and a positive number your answer is essentially adding two negative numbers and your answer will be negative. Ex. -12-6= or -12+-6= -18
Subtracting continued • IMPORTANT THINGS TO REMEMBER! • When you have two negatives in a row (a subtraction sign and a negative sign) it cancels each other out and changes to a positive. Ex. 6-(-4)= There are two negatives in a row so it changes to 6+4=10 Just like English- you cannot have a double negative in a sentence! What about -2-(-7)?
Problems • -6-3= • -8-(-8)= • 7-12= If n=-3 evaluate each expression. 4. n-(-19)= 5. -1-n= 6. 7- l n l –(-11)=