SOLUTION: is x suppose to equal a number that should replace the x or is it all ways one

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Question 384088: is x suppose to equal a number that should replace the x or is it all ways one
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
In a general expression, x represents any number.

To solve for a specific number, you replace x with that number in the equation.

example:

y = x^2 + 3*x - 5

If you want to know the value of y when x = 3, you replace x with 3 in the equation to get:

y = 3^2 + 3*3 - 5 = 9 + 9 - 5 = 18 - 5 = 13

When you get into functional notation (if not already), then you will see:

f(x) = x^2 + 3*x - 5

When x = 3, then you will see:

f(3) = 3^2 + 3*3 - 5

The 3 replaces the x to give you the value of the equation when x = 3.

If you want to know the value of y or f(x), when x = 5, then you replace x with 5, etc.