EVALUATING EXPONENTS Let’s review the odd/even rule with and without ( ): EVEN POWERS: (2) 2 2 2 2 16 4 2 4 2 2 2 2 16 In this first one, BOTH the negative sign and the 2 are to the 4th power so there are 4 negatives (even number so positive). In the second one, ONLY the 2 is to the 4th power because there are no ( )…I call the negative sign a ZAPPER! AFTER you simplify the power, then think of the negative sign as multiplying by -1. In order of operations, you do the power first and multiply by -1 AFTER you simplify the power. Let’s review the odd/even rule with and without ( ): ODD POWERS: ( 2) 2 2 2 8 3 2 3 2 2 2 8 So for different reasons, negative bases raised to an ODD power are ALWAYS NEGATIVE! In the first one, BOTH the negative sign and the 2 are to the 3rd power…so there are 3 negatives, which is an odd number. The answer is NEGATIVE. In the second one, ONLY the 2 is to the 3rd power…the negative sign is a ZAPPER. AFTER you simplify the power, you multiply by -1. There is only 1 negative in this problem and 1 is an odd number so the answer is NEGATIVE. So now you try these: (2) 64 6 negatives is POSITIVE 2 32 1 negative is NEGATIVE 6 5 2 64 6 There is ONLY 1 NEGATIVE! WHY? When there are no ( ), only the base is raised to the power and the negative sign is the same as multiplying by a -1 AFTER the power is simplified…therefore the answer is NEGATIVE (2) 32 5 There are 5 negatives. Why? When the negative is inside the ( ), it’s raised to the power of 5. An odd number of negatives is NEGATIVE TRY THIS: (2) 64 6 How many negatives are there in this problem? 7 (which is odd). There are 6 negatives from the power and another negative (a zapper) outside the ( ) (2) 32 5 How many negatives are there in this problem? 6 (which is even). There are 5 negatives from the power and another negative (a zapper) outside the ( ) Try this: 16(9 11) 4 2 3 DO NOT DISTRIBUTE THE 16 BECAUSE ORDER OF OPERATIONS TELLS YOU THAT YOU MUST SIMPLIFY THE POWER (squared) BEFORE YOU CAN MULTIPLY! Do what’s in the ( ) first: 16(9 11) 16(2) 4 4 2 3 2 3 Now simplify the exponents: 16(2) 16(4) 4 64 2 3 Simplify the numerator: 16(4) 64 64 64 Once the numerator and denominator are simplified, simplify the fraction: 64 1 64 TRY THIS: (30 3 5) (25) 2 2 DO NOT DISTRIBUTE THE FIRST NEGATIVE SIGN UNTIL AFTER YOU SIMPLIFY WHAT’S INSIDE THE PARENTHESES AND AFTER YOU SIMPLIFY THE OUTSIDE EXPONENT. Do the exponent inside the ( ) and ++ for the 25: (30 3 5) (25) (30 9 5) 25 2 2 2 Keep simplifying in the ( ): (30 9 5) 25 (30 45) 25 2 2 Keep simplifying in the ( ): (30 45) 25 (15) 25 2 2 Now do the power: (15) 25 (225) 25 2 Add: (225) 25 200 TRY THIS: x 3 y 4 ( x 2) ( y 2) 2 3 REMEMBER: You always plug in negative numbers with ( ) x 3 y 4 ( x 2) ( y 2) 2 3 [(3) 2] [(4) 2] 2 3 [3 2] [6] 2 (1) (6) 2 3 3 (1)(216) 216 You always plug in negative numbers with ( )! You can go + + on the 3 because the power is on the OUTSIDE. Simplify the ( ) Simplify the exponents Multiply TRY THIS: x 3 y 4 xy 2 Only the y is raised to the 2nd power x 3 y 4 xy 2 (3)(4) (3)(4) 3(16) 48 2 2 Plug in negative bases in ( ) You can do ++ on the 3 because it’s not raised to a power The -4 is squared so it is +16 because it’s an even power Multiply TRY THIS: x 3 y 4 x x x x 4 x (9) 5 4 3 2 Make sure you always simplify the EXPONENT 1st, then apply the negative sign given in the problem…In other words, YOU CAN’T GO + + BEFORE YOU DO THE EXPONENT INSIDE THE ( )!!! x 3 y 4 x x x x 4 x (9) 5 4 2 3 Plug in the negative base in ( ): (3) (3) (3) (3) 4(3) (9) 5 4 3 2 Simplify the exponents: (243) (81) (27) (9) 12 9 Simplify the negative signs and add: 243 81 27 9 12 9 219 TRY THIS: x 5 and y 3 ( x y) x y 2 2 2 x 5 and y 3 ( x y) x y 2 (5 (3)) (5) (3) 2 2 2 2 (5 3) 25 (9) (8) 16 2 2 64 4 16 2 Plug in the negative base in ( ) Numerator: Simplify inside the ( ) Denominator: Simplify the exponents Numerator: Simplify inside the ( ) Denominator: Add Numerator: Simplify the exponents Finally: Simplify the fraction
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