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!! :)
Answer:
9
Step-by-step 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.
