High School Math : Understanding Polynomial Functions

Study concepts, example questions & explanations for High School Math

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1 : Understanding Polynomial Functions

It took Jack 25 minutes to travel 14 miles, what was Jack's average speed in mph?

Possible Answers:

\(\displaystyle 2.4\ mph\)

\(\displaystyle 1.78\ mph\)

\(\displaystyle 30.21\ mph\)

\(\displaystyle 33.6\ mph\)

Correct answer:

\(\displaystyle 33.6\ mph\)

Explanation:

\(\displaystyle speed=\frac{distance}{time}\)

\(\displaystyle speed=\frac{14\ miles}{25\ minutes }\)

* We have to change the time from minutes to hours, there are 60 minutes in one hour. 

\(\displaystyle speed= \frac{14\ miles}{25\ minutes} * \frac{60\ minutes}{1\ hour}\)

\(\displaystyle speed= 33.6\ mph\)

 

Example Question #2 : Understanding Polynomial Functions

Let \(\displaystyle f(x)=3x^{2}-2\) and \(\displaystyle g(x)= x+2\).  Evaluate \(\displaystyle f(g(3))\).

Possible Answers:

\(\displaystyle 89\)

\(\displaystyle 54\)

\(\displaystyle 27\)

\(\displaystyle 73\)

\(\displaystyle 108\)

Correct answer:

\(\displaystyle 73\)

Explanation:

Substitute \(\displaystyle 3\) into \(\displaystyle g(x)\), and then substitute the answer into \(\displaystyle f(x)\).

\(\displaystyle g(x)= x+2\) 

\(\displaystyle g(3)=3+2=5\)

\(\displaystyle f(x)= 3x^{2}-2\) 

\(\displaystyle f(5) =3(5)^{2}-2= 75 -2 = 73\)

Example Question #2 : Understanding Polynomial Functions

Solve the following system of equations:

\(\displaystyle -x-3y= 4\)

\(\displaystyle 2x+5y=7\)

Possible Answers:

\(\displaystyle \left ( 1,-5 \right )\)

Infinite solutions.

\(\displaystyle \left ( 2,4 \right )\)

\(\displaystyle \left ( 41,-15 \right )\)

\(\displaystyle \left ( -4,10 \right )\)

Correct answer:

\(\displaystyle \left ( 41,-15 \right )\)

Explanation:

We will solve this system of equations by Elimination.  Multiply both sides of the first equation by 2, to get:

\(\displaystyle -2x-6y=8\)

Then add this new equation, to the second original equation, to get:

\(\displaystyle -y = 15\)

or 

\(\displaystyle y=-15\)

 

Plugging this value of \(\displaystyle y\) back into the first original equation, gives:

\(\displaystyle -x-3(-15) = 4\)

\(\displaystyle -x = 4- 45\)

or 

\(\displaystyle x = 41\)

Learning Tools by Varsity Tutors