8th Variables and Expressions

To evaluate an expresion means to find its value To avoid confusion, mathematicians have agreed to a set of called the order of operations. When you a number for the variable, an algebraic expression becomes a numericalexpression. A variable is a , usually a letter, used to represent a . An algebraic expression contains a , a number, and at least one symbol. substitute ? number ? symbol ? operation ? variable ? numeric ? Evaluate each expression if q = 5, r = 6 and s = 3. 4(r - s) ^{2}^{}=4 = 4 ( ) ^{2}^{}^{}^{= 4 x }^{}^{}^{= }( 36 ? 6 ? 9 ? 3 ? - 3 ) ^{2}← ← ← Perform operations in the first. Evaluate the power. Simplify Replace with 6 and with 3. parentheses ? s ? r ? Expressions such a 7 ^{2} and 2^{3} are called powersand represent repeated Remember q = 5, r = 6 and s = 3. = ( q^{2} - 4r - 15 ? = = = ) 2 25 25 ? 1 ? - 4 - - 4(6) -1 - 1 ( 24 ? 6 ? ) - 1 - 1 ← replace the q with 5 replace the r with 6 Since you have no parentheses you must evaluate the exponents first Work from left to right when operations are the same. |

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