SOLUTION: I would really like it if you help me in the following function notations questions. Consider the function f(x)=5–x, Evaluate f(21) Consider the function f(x)=3x+5.Evaluate

Algebra ->  Functions -> SOLUTION: I would really like it if you help me in the following function notations questions. Consider the function f(x)=5–x, Evaluate f(21) Consider the function f(x)=3x+5.Evaluate      Log On


   

Question 930414: I would really like it if you help me in the following function notations questions.
Consider the function f(x)=5–x, Evaluate f(21)
Consider the function f(x)=3x+5.Evaluate f(2)

Consider the function f(x)=5x–1
Determine the value of x if f(x)=9
Consider the function f(x)=x+3
Determine the value of x if f(x)=10
It would be great if you help me. :) Thanks for your time. I appreciate it! :)
Answer by algebrahouse.com(1659) About Me  (Show Source):
You can put this solution on YOUR website!
f(x) = 5 - x
f(21) = 5 - 21 {substituted 21 for x}
= -16 {subtracted}

f(x) = 3x + 5
f(2) = 3(2) + 5 {substituted 2 for x}
= 6 + 5 {multiplied}
= 11 {added}

f(x) = 5x - 1
If f(x) = 9, then 5x - 1 = 9
5x - 1 = 9
5x = 10 {added 1 to each side}
x = 2 {divided each side by 5}

f(x) = x + 3
If f(x) = 10, then x + 3 = 10
x + 3 = 10
x = 7 {subtracted 3 from each side}

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