document.write( "Question 893224: what are differences between expressions and functions? if we can find solution to expression in order to find the variable why functions were introduced? \n" ); document.write( "

Algebra.Com's Answer #541171 by josgarithmetic(39617) $\"\"$ $\"About$

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An expression is like a phrase or a clause; a function is like a sentence.\r
\n" ); document.write( "\n" ); document.write( "One can evaluate an expression; and one can evaluate a function for a given value for an input variable.\r
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\n" ); document.write( "\n" ); document.write( "Another attempt:\r
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\n" ); document.write( "\n" ); document.write( "An expression is a number. The number can be written with plain numbers and variables, or it can be written just in variables.
\n" ); document.write( " $\"x%5E2\"$ , $\"4%281%2F2%29-3x\"$ , $\"x%5E3%2B13\"$ , or any such way of writing a number is an expression.\r
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\n" ); document.write( "\n" ); document.write( "A function is, for your purpose, a statement usually using symbols and numbers, that some number with a name is equal to an expression. The name for the function is given a letter like f, or g, or h, or sometimes other letters.
\n" ); document.write( "f(x) or g(x) or h(x) is a name of a function. A function is often written as an equation, for example:
\n" ); document.write( " $\"f%28x%29=%28x-3%29%5E2\"$ or $\"f%28x%29=%28x%2B10%29%2F%282x-1%29\"$ or $\"g%28x%29=x%5E2\"$ .
\n" ); document.write( "The left side of the equation is a number. The right side of the equation is a number.\r
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\n" ); document.write( "\n" ); document.write( "We can use functions to say that a quantity (the name of the function) depends on the value of a variable.
\n" ); document.write( "If we have a function like $\"f%28x%29=x%5E2\"$ , then this means the value of f depends on the value of x.
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\n" ); document.write( "If we want x=-3, then we can find $\"f%28-3%29=%28-3%29%5E2\"$ , which means $\"f%28-3%29=9\"$ .
\n" ); document.write( "If we want x=7, then we can find $\"f%287%29=%287%29%5E2\"$ , which is $\"f%287%29=49\"$ . \n" ); document.write( "

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