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Example Questions
Example Question #2811 : Sat Mathematics
If , what is the smallest possible value of
?
8
4
6
10
12
6
This equation describes a parabola whose vertex is located at the point (4, 6). No matter how large or small the value of t gets, the smallest that f(t) can ever be is 6 because the parabola is concave up. To prove this to yourself you can plug in different values of t and see if you ever get anything smaller than 6.
Example Question #2812 : Sat Mathematics
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.
Example Question #2813 : Sat Mathematics
Let and
be functions such that
, and
. Which of the following is equal to
?
If and
are defined as inverse functions, then
. Thus, according to the definition of inverse functions,
and
given in the problem must be inverse functions.
If we want to find the inverse of a function, the most straighforward method is usually replacing with
, swapping
and
, and then solving for
.
We want to find the inverse of . First, we will replace
with
.
Next, we will swap and
.
Lastly, we will solve for . The equation that we obtain in terms of
will be in the inverse of
, which equals
.
We can treat as a proportion,
. This allows us to cross multiply and set the results equal to one another.
We want to get y by itself, so let's divide both sides by x.
Next, we will add 3 to both sides.
To combine the right side, we will need to rewrite 3 so that it has a denominator of .
The answer is .
Example Question #987 : Psat Mathematics
.
Example Question #2814 : Sat Mathematics
Let the function f be defined by f(x)=x-t. If f(12)=4, what is the value of f(0.5*t)?
First we substitute in 12 for x and set the equation up as 12-t=4. We then get t=8, and substitute that for t and get f(0.5*8), giving us f(4). Plugging 4 in for x, and using t=8 that we found before, gives us:
f(4) = 4 - 8 = -4
Example Question #332 : Algebra
What is the value of the function f(x) = 6x2 + 16x – 6 when x = –3?
0
–108
–12
96
0
There are two ways to do this problem. The first way just involves plugging in –3 for x and solving 6〖(–3)〗2 + 16(–3) – 6, which equals 54 – 48 – 6 = 0. The second way involves factoring the polynomial to (6x – 2)(x + 3) and then plugging in –3 for x. The second way quickly shows that the answer is 0 due to multiplying by (–3 + 3).
Example Question #2815 : Sat Mathematics
Given the functions f(x) = 2x + 4 and g(x) = 3x – 6, what is f(g(x)) when x = 6?
16
192
144
28
12
28
We need to work from the inside to the outside, so g(6) = 3(6) – 6 = 12.
Then f(g(6)) = 2(12) + 4 = 28.
Example Question #36 : Algebraic Functions
A function f(x) = –1 for all values of x. Another function g(x) = 3x for all values of x. What is g(f(x)) when x = 4?
12
–1
–3
3
–12
–3
We work from the inside out, so we start with the function f(x). f(4) = –1. Then we plug that value into g(x), so g(f(x)) = 3 * (–1) = –3.
Example Question #37 : Algebraic Functions
What is f(–3) if f(x) = x2 + 5?
–14
14
4
15
–4
14
f(–3) = (–3)2 + 5 = 9 + 5 = 14
Example Question #2816 : Sat Mathematics
For all values of x, f(x) = 7x2 – 3, and for all values of y, g(y) = 2y + 9. What is g(f(x))?
14x2 – 3
14y2 + 3
7y2 – 3
14x2 + 3
2x + 9
14x2 + 3
The inner function f(x) is like our y-value that we plug into g(y).
g(f(x)) = 2(7x2 – 3) + 9 = 14x2 – 6 + 9 = 14x2 + 3.
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