Question

Use the function r(x)=2x+1
if r(b)=19 what is the value of b?

Answer 1

9

Explanation:

They are asking what value of x can you input into 2x+1 so that the outpot is 19.

In other words, you need to solve 2x+1=19.

Subtracting 1 on both sides gives: 2x=18.

Dividing 2 on both sides gives: x=9.

So r(9)=19 since 2(9)+1 is 19.

Answer 2

Let's think of this like a point. We know the y-value, but not the x-value. Therefore, in order to find b, we should plug in our known y-value, 19, for r(x).

19 = 2b + 1 || We can leave it as x in our equation or change it to b. Either way you will get the same answer. I changed it to b in this case just to follow through with what the question is asking.

18 = 2b

b = 9

Hope this helps!! :)