All PSAT Math Resources
Example Questions
Example Question #961 : Psat Mathematics
if and , solve .
We are solving for a composite function by substituting into to get: before simplification.
Example Question #78 : Algebraic Functions
If where is an integer, which of the following could be a value of ?
I.
II.
III.
II only
I and III only
II and III only
I only
I, II and III
II and III only
Choice I is incorrect because to equal 0, , and since is an integer, this cannot be true.
Choice II is correct because when or .
Choice III is correct because when or .
Example Question #272 : New Sat
Jamie is three times her little brother's age, and her little brother is two years younger than his older brother. Collectively, the three of them are 27 years old. How old is Jamie?
None of the available answers
The algebraic expression for being Jamie's youngest brother's age is:
Jamie's youngest brother is five, the next oldest brother is seven, and Jamie is 15.
Example Question #962 : Psat Mathematics
Consider the function defined as follows:
Find:
The notation used above can be confusing. Let:
We can now find the answer by substituting the appropriate values into the equation:
Therefore:
Finally:
Example Question #963 : Psat Mathematics
Solve for .
To solve for , we actually have to solve for , when . We simply replace any with a .
The answer of when is .
Example Question #1 : Algebraic Functions
If f(x)=3x and g(x)=2x+2, what is the value of f(g(x)) when x=3?
24
18
22
20
24
With composition of functions (as with the order of operations) we perform what is inside of the parentheses first. So, g(3)=2(3)+2=8 and then f(8)=24.
Example Question #2 : Algebraic Functions
g(x) = 4x – 3
h(x) = .25πx + 5
If f(x)=g(h(x)). What is f(1)?
4
π + 17
13π + 3
19π – 3
42
π + 17
First, input the function of h into g. So f(x) = 4(.25πx + 5) – 3, then simplify this expression f(x) = πx + 20 – 3 (leave in terms of π since our answers are in terms of π). Then plug in 1 for x to get π + 17.
Example Question #411 : Algebra
If 7y = 4x - 12, then x =
Adding 12 to both sides and dividing by 4 yields (7y+12)/4.
Example Question #3 : Algebraic Functions
What is ?
Example Question #4 : Algebraic Functions
If F(x) = 2x2 + 3 and G(x) = x – 3, what is F(G(x))?
6x2 – 12x
2x2
2x2 – 12x +21
2x2 + 12x +18
6x2 + 5x
2x2 – 12x +21
A composite function substitutes one function into another function and then simplifies the resulting expression. F(G(x)) means the G(x) gets put into F(x).
F(G(x)) = 2(x – 3)2 + 3 = 2(x2 – 6x +9) + 3 = 2x2 – 12x + 18 + 3 = 2x2 – 12x + 21
G(F(x)) = (2x2 +3) – 3 = 2x2
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