All ACT Math Resources
Example Questions
Example Question #6 : How To Find F(X)
Let F(x) = x3 + 2x2 – 3 and G(x) = x + 5. Find F(G(x))
x3 + 17x2 + 95x + 172
x3 + x2 + 2
x3 + x2 + x + 8
x3 + 2x2 – x – 8
x3 + 2x2 + x + 2
x3 + 17x2 + 95x + 172
F(G(x)) is a composite function where the expression G(x) is substituted in for x in F(x)
F(G(x)) = (x + 5)3 + 2(x + 5)2 – 3 = x3 + 17x2 + 95x + 172
G(F(x)) = x3 + x2 + 2
F(x) – G(x) = x3 + 2x2 – x – 8
F(x) + G(x) = x3 + 2x2 + x + 2
Example Question #7 : How To Find F(X)
What is the value of xy2(xy – 3xy) given that x = –3 and y = 7?
2881
–6174
3565
–2881
–6174
Evaluating yields –6174.
–147(–21 + 63) =
–147 * 42 = –6174
Example Question #4 : Algebraic Functions
Find .
is . To start, we find that . Using this, we find that .
Alternatively, we can find that . Then, we find that .
Example Question #8 : How To Find F(X)
It takes no more than 40 minutes to run a race, but at least 30 minutes. What equation will model this in m minutes?
If we take the mean number of minutes to be 35, then we need an equation which is less than 5 from either side of 35. If we subtract 35 from minutes and take the absolute value, this will give us our equation since we know that the time it takes to run the marathon is between 30 and 40 minutes.
Example Question #1181 : Algebra
If and , what is ?
Example Question #1182 : Algebra
If and , which of the following could represent ?
The number in the parentheses is what goes into the function.
For the function ,
and
Example Question #11 : How To Find F(X)
A function F is defined as follows:
for x2 > 1, F(x) = 4x2 + 2x – 2
for x2 < 1, F(x) = 4x2 – 2x + 2
What is the value of F(1/2)?
For F(1/2), x2=1/4, which is less than 1, so we use the bottom equation to solve. This gives F(1/2)= 4(1/2)2 – 2(1/2) + 2 = 1 – 1 + 2 = 2
Example Question #31 : Algebraic Functions
Which of the statements describes the solution set for –7(x + 3) = –7x + 20 ?
There are no solutions.
All real numbers are solutions.
x = –1
x = 0
There are no solutions.
By distribution we obtain –7x – 21 = – 7x + 20. This equation is never possibly true.
Example Question #1183 : Algebra
Will just joined a poetry writing group in town that meets once a week. The number of poems Will has written after a certain number of meetings can be represented by the function , where represents the number of meetings Will has attended. Using this function, how many poems has Will written after 7 classes?
For this function, simply plug 7 in for and solve:
Example Question #13 : How To Find F(X)
If , then ?
To find when , we substitute for in .
Thus, .
We expand to .
We can combine like terms to get .
We add 3 to this result to get our final answer.