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Learning how to write and solve algebraic expressions. Important Terms. Terms Definition Example. Variable Using a letter to represent n, x, or k a number. Expression A number, variable, or any 2 + n
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Important Terms TermsDefinitionExample VariableUsing a letter to represent n, x, or k a number ExpressionA number, variable, or any 2 + n combination of numbers, variables and operation signs. Evaluate (Solve)To put in the value for n = 8 variable and perform the 2 + 8 = 10 operation to find the answer
You will have a number, a variable, and an operation sign 8 + n When writing an expression Variable Number Operation
8 + n Write out the number, put in a word or phrase that means the operation, and write some number or a number when writing the variable. DO NOT put the letter (n, x, p). Eight increased by some number Writing the Expression in Words Variable Number operation Variable Number operation
Whenever you see the words Than, To, From in an expression that means you have to flip the places of the number and variable. • Subtract 9 from some number X – 9 Than, to, from Variable Number Operation
Kim has 5 less pumpkins than Fred. We can use a variable (a letter like x or p) to stand for the number of pumpkins Fred has. Let’s write an expression
We can compare the number of pumpkins Fred has with number of pumpkins Kim has by using a mathematical expression that uses a variable. Mathematical expressions that use variables are called algebraic expressions.
Let’s write this as an algebraic expression. Let’s use p as a variable to represent the number of pumpkins Fred has. 5 less tells us the number we should use and the operation. p - 5
Let’s evaluate the expression by putting in a value for our variable. Let’s say Fred has 15 pumpkins . That means that we now know that p = 15. Now we can figure out how many pumpkins Kim has. P=15 P - 5 = K 15 – 5 = k K = 10
Let’s write an algebraic expression in words. n – 3 Some number minus three or some number subtract three
Write an algebraic expression for each word phrase. Some number plus 6 8 less than a number
When evaluating expressions just plug in the number for the variable. k + 13 k = 7 7 + 13 7 + 13 = 20 evaluating expressions
Change each algebraic expression into words. Then evaluate when n = 4 • n + 9 • 11 – n • 14 + r • P - 4 Solving expressions
Will these expressions give us the same answer if we substitute the same number for the variable? 8 plus a number 8 more than some number
Will these expressions give us the same answer if we substitute the same number for the variable. 8 less than a number some number minus 8
http://www.teachervision.fen.com/tv/printables/Math_5_PS_5-8.pdfhttp://www.teachervision.fen.com/tv/printables/Math_5_PS_5-8.pdf http://itech.pjc.edu/falzone/worksheets/translate_phrases_to_var_expr1.pdf Worksheet websites