   SEARCH HOME Math Central Quandaries & Queries  Subject: Function y= 5 x - 3 Name: Richard Who are you: Parent Question is the function y = 5 x - 3 for the given value of x 7 , 1 or 4 Please help me understand to help teach my daughter(Brat) Richard,

In the expression y = 5x - 3 there is an implicit multiplication between the 5 and the x so as an instruction 5x - 3 says "multiply 5 by the value of x and then subtract 3". So for example if x = 2 then

5x - 3 = 5 2 - 3 = 10 - 3 = 7

and if x = -4 then

5x - 3 = 5 (-4) - 3 = -20 - 3 = -23

Penny

Hello Richard.

I can't quite answer your question because you haven't said what the "given" value of x is.

These questions are usually worded more like this:
What is the value of the function y = 5 x - 3 for the given value of x = 2.

In this case, the answer would be 7 because 5 times 2 minus 3 is 7. You put the given value of x in place of x and do the calculation.

or

What is the value of the function y = 5 x - 3 for the following given
values of x: 7, 1 and 4.

In this other case, there are three answers: one for each value of x. Try it with 7 in place of x and you get 5 times 7 minus 3 is 32; with x = 1, the value of the function is 2; with x = 4, the value of the function is 17.

Check the wording carefully to see what it is asking and what value(s) of x are given to you.

Hope this helps,
Stephen La Rocque.     Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.