Welcome back! Sit down and work on the warm up!

Transcription

1 Welcome back! Sit down and work on the warm up! 1 Rewrite using exponents 2 Circle the coefficient and square the constant of the function y=3x+7 3 Rewrite the expression using multiplication: What has a thumb and 4 fingers but is not alive? 5 Write an expression for the value of Brennan's change in cents "Brennan has m dimes in his pocket He also has 27 cents in other coins" Mar 23 3:40 PM

2 Objectives: I can recognize mathematical symbols the calculator uses I can solve problems with rational numbers involving natural exponents I can change an expression using math properties Planner: 81C is due: 81 Quiz: Mar 21 3:40 PM

3 Lesson 81C Expressions & Multiplication I can recognize mathematical symbols the calculator uses 7233 I can solve problems with rational numbers involving natural exponents 7123 I can change an expression using math properties x t 6 t 6(t) 6t These are all ways of writing six multiplied by the variable, t You know that you can use exponents or powers to make a number multiply by itself 5 2 means 5(5) 5 2 is read as 5 squared, or 5 to the second power, or 5 to the power of means 5(5)5 5 3 is read as 5 cubed, or 5 to the third power, or 5 to the power of means (5)(5)(5)(5) 5 4 is read as 5 to the fourth power or 5 to the power of 4 Variables can also be written with exponents 2 s s s is the same as 2s 3 careful (2s) 3 is different then 2s 3 (2s) 3 that means (2s)(2s)(2s) Exponent Visual Demonstration resource/ vtl07mathnumberexplilyescape/lilypad escape/ 3 minutes long Rewrite the expression using exponents: 1) 3 p p p 2) 5 x x y y y 3) r r r r r r r 4 Order of Operation: Grouping Symbols Exponents Multiplication & Division from the left to the right Addition & Subtraction from the left to the right Sep 23 11:00 AM

4 Most calculators apply the order of operations for you Some DO NOT you need to check if yours does Try this to find out: 7 + 8(5) Your answer: Calculator answer: Parentheses ( ) can be used to change the order that you perform the operations They can be put into an expression to force you to do an operation you would not normally do first Where would you put the parentheses to get an answer of 27 in the following expression? Calculators and Exponential Functions: Scientific calculators have a key which allows you to raise a number to a power There are several different ways the raise to the power key can appear on your calculator depending on which calculator you have Here are a few of the most common x y y x x^y y^x x ^ 7th Grade MCA calculator In order to use the raised to the power of button you must: 1 Input (type in) the base number 2 Push the raise to the power of button 3 Input the exponent number 4 Push = or Enter When you study mathematics, it is important to know the shortcuts that are used for writing expressions You already know that when you want to show a number times a variable, you can leave out the multiplication sign Instead of 6 x t or 6 t, you can write 6t Note that the number is normally placed before the variable What if you want to show that the variable t is multiplied by itself? You could write t x t, t t or tt However, an exponent is usually used to tell how many times a quantity is multiplied by itself So, t x t is written t 2, and t t t is written t 3 Here are some other examples The expression 2 s s s is written 2s 3 The expression m 5 m is written 5m 2 The expression 2 p p p is written 2p 3 The expression x x y 7 is written 7x 2 y or 7yx 2 It is also important to understand the rules for evaluating, or finding the value of, expressions You learned some of these rules when you studied arithmetic Repeated + Repeated x think think x exponent Sep 23 11:00 AM

5 Rewrite each expression without using multiplication or addition signs 4) r + r 5) r r 6) t + t + t 7) 5 g g g 8) 5s + s 9) 25m m 10) Insert parentheses, if necessary (needed), so the resulting expression equals ) Insert parentheses, if necessary, so the resulting expression equals ) Write an expression that means "take a number, multiply it by 6, and cube the result (answer)" Evaluate each expression for r = 3 13) 5r 2 14) (5r) 2 15) 2r 4 16) (2r) 4 17) When Kate, Jin Lee, Darnell, Zach, and Maya tried to find the value of 3t 2 for t = 7, they came up with five different answers Only one of their answers is correct Kate: t 2 = 49, so 3t 2 = 349 Jin Lee: 3t 2 = = 42 Darnell: 3t 2 = = 3 49 = 147 Zach: 3t 2 = 37 2 = 1,369 Maya: 3t 2 = = 21 2 = 441 Sep 23 1:07 PM