Algebra 1 : Algebraic Functions

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #31 : Algebraic Functions

Define \(\displaystyle f (x) = 3 - \sqrt{x-1}\) and \(\displaystyle g\left ( x\right ) = 3 + \sqrt{x-1}\).

Evaluate \(\displaystyle \left (f-g \right ) (17)\).

Possible Answers:

\(\displaystyle 8\)

\(\displaystyle \left (f-g \right ) (17)\) is undefined.

\(\displaystyle 6\)

\(\displaystyle -6\)

\(\displaystyle -8\)

Correct answer:

\(\displaystyle -8\)

Explanation:

First evaluate \(\displaystyle f (17)\) and \(\displaystyle g(17)\), then subtract.

\(\displaystyle f (x) = 3 - \sqrt{x-1}\)

\(\displaystyle f (17) = 3 - \sqrt{17-1} = 3 - \sqrt{16} = 3-4 = -1\)

 

\(\displaystyle g\left ( x\right ) = 3 + \sqrt{x-1}\)

\(\displaystyle g(17) = 3 + \sqrt{17-1} = 3 + \sqrt{16} = 3+4 = 7\)

 

\(\displaystyle \left (f-g \right ) (17) = f(17)-g(17) = -1-7 = -8\)

Example Question #31 : Algebraic Functions

If \(\displaystyle f(x) = 2x^2 - 4x +1\), then which of the following is equivalent to \(\displaystyle f(t + 2)\)?

Possible Answers:

\(\displaystyle t^2 - 4t + 1\)

\(\displaystyle 2t^2 + 4t + 17\)

\(\displaystyle 2t^2 + 4t + 1\)

\(\displaystyle t^2 + 4t + 1\)

\(\displaystyle 2t^2 + 4t + 5\)

Correct answer:

\(\displaystyle 2t^2 + 4t + 1\)

Explanation:

Plug in \(\displaystyle (t+2)\) for \(\displaystyle x\).

 \(\displaystyle f(x) = 2x^2 - 4x +1\)

\(\displaystyle x=t+2\)

\(\displaystyle f(t+2) = 2(t+2)^2 - 4(t+2) +1\)

FOIL the squared term and distribute -4:

\(\displaystyle 2(t^2+2t+2t+4)-4t-2+1\)

Distribute the 2:

\(\displaystyle 2t^2+8t+8-4t-2+1\)

Combine like terms:

\(\displaystyle 2t^2 + 4t + 1\)

 

Example Question #33 : Algebraic Functions

Define \(\displaystyle g (x) = 5x +7\) .

If \(\displaystyle g (A) = 24\), evaluate \(\displaystyle A\).

Possible Answers:

\(\displaystyle A = 3.4\)

\(\displaystyle A=6.2\)

\(\displaystyle A=127\)

\(\displaystyle A = 11.8\)

\(\displaystyle A=113\)

Correct answer:

\(\displaystyle A = 3.4\)

Explanation:

Plug in \(\displaystyle A\) as if it were a constant, and then solve for its value:

\(\displaystyle g (A) = 5A +7 = 24\)

\(\displaystyle 5A +7 - 7 = 24-7\)

\(\displaystyle 5A = 17\)

\(\displaystyle 5A \div 5 = 17\div 5\)

\(\displaystyle A = 3.4\)

Example Question #32 : Algebraic Functions

\(\displaystyle \left \lceil x \right \rceil\) is defined as the least integer greater than or equal to \(\displaystyle x\)

Define \(\displaystyle f(x) = \left \lceil x^{2} + x + 2 \right\rceil\).

Evaluate \(\displaystyle f(5.5)\).

Possible Answers:

\(\displaystyle f(5.5) = 33\)

\(\displaystyle f(5.5) = 38\)

\(\displaystyle f(5.5) = 35\)

\(\displaystyle f(5.5) = 37\)

\(\displaystyle f(5.5) = 32\)

Correct answer:

\(\displaystyle f(5.5) = 38\)

Explanation:

\(\displaystyle f(x) = \left \lceil x^{2} + x + 2 \right\rceil\)

Plug in 5.5:

\(\displaystyle f(5.5) = \left \lceil 5.5^{2} + 5.5 + 2 \right\rceil\)

\(\displaystyle f(5.5) = \left \lceil 30.25 + 5.5 + 2 \right\rceil\)

\(\displaystyle f(5.5) = \left \lceil 37.75 \right\rceil = 38\)

Example Question #34 : Algebraic Functions

\(\displaystyle f\left ( x \right ) = \sqrt{x}\)

\(\displaystyle g\left ( x \right ) = 2x-3\)

\(\displaystyle h\left ( x \right ) = x^{2}\)

Find \(\displaystyle f\left ( g\left ( h\left ( x \right ) \right ) \right )\).

Possible Answers:

\(\displaystyle 2x^{2}-3\)

\(\displaystyle 2x-3\)

\(\displaystyle \sqrt{2x^{2}-3}\)

\(\displaystyle x\)

\(\displaystyle \sqrt{x^{3}}\)

Correct answer:

\(\displaystyle \sqrt{2x^{2}-3}\)

Explanation:

Plug \(\displaystyle h(x)\) into \(\displaystyle g(x)\).

\(\displaystyle g\left ( x \right ) =2x-3\)

\(\displaystyle g\left ( h\left ( x \right ) \right ) = 2\times h(x) - 3 = 2x^{2} - 3\)

Now plug that into \(\displaystyle f(x)\):

\(\displaystyle f\left ( g\left ( h\left ( x \right ) \right ) \right )= \sqrt{g(h(x))} = \sqrt{2x^{2}-3}\)

Example Question #3367 : Algebra 1

Solve for \(\displaystyle f(x)\). When \(\displaystyle x=2\)

\(\displaystyle f(x)=5x^3+2x-24\)

Possible Answers:

\(\displaystyle f(x)=14\)

\(\displaystyle f(x)=20\)

\(\displaystyle f(x)=10\)

\(\displaystyle f(x)=-20\)

\(\displaystyle f(x)=-15\)

Correct answer:

\(\displaystyle f(x)=20\)

Explanation:

Given the equation,

 \(\displaystyle f(x)=5x^3+2x-24\) and  \(\displaystyle x=2\)

Plug in \(\displaystyle 2\) for \(\displaystyle x\) to the equation, \(\displaystyle f(2)=5(2)^3+2(2)-24\) 


Solve and simplify. 


\(\displaystyle f(2)=5(8)+4-24\)

\(\displaystyle f(2)=40+4-24\)

\(\displaystyle f(2)=44-24\)

\(\displaystyle f(2)=20\)

Example Question #3371 : Algebra 1

\(\displaystyle f(x)=\frac{4x-2}{x+3}, x\neq-3\)

Solve for \(\displaystyle f(x)\), when \(\displaystyle x=0\).

Possible Answers:

\(\displaystyle f(x)=\frac{-1}{3}\)

\(\displaystyle f(x)=\frac{1}{3}\)

\(\displaystyle f(x)=\frac{2}{3}\)

\(\displaystyle f(x)=0\)

\(\displaystyle f(x)=\frac{-2}{3}\)

Correct answer:

\(\displaystyle f(x)=\frac{-2}{3}\)

Explanation:

\(\displaystyle f(x)=\frac{4x-2}{x+3}, x\neq-3\)

Plug in the \(\displaystyle x\) value for \(\displaystyle x\).

\(\displaystyle f(0)=\frac{4(0)-2}{(0)+3}\)

Simplify

\(\displaystyle f(0)=\frac{0-2}{3}\)

Subtract

\(\displaystyle f(0)=\frac{-2}{3}\)

Example Question #32 : Algebraic Functions

For the following equation, if x = 2, what is y?

\(\displaystyle y=x^3-4x+9\)

Possible Answers:

7

16

1

25

9

Correct answer:

9

Explanation:

On the equation, replace x with 2 and then simplify.

\(\displaystyle y=x^3-4x+9\)

\(\displaystyle y=(2)^3-4(2)+9\)

\(\displaystyle y=8-8+9\)

\(\displaystyle y=9\)

Example Question #33 : Algebraic Functions

Solve for \(\displaystyle f(3)\) when \(\displaystyle f(x)= \frac{x^{2}+12x}{3x}\).

Possible Answers:

\(\displaystyle f(3)=3\)

\(\displaystyle f(3)=5\)

\(\displaystyle f(3)=16\)

\(\displaystyle f(3)=9\)

Does not exist

Correct answer:

\(\displaystyle f(3)=5\)

Explanation:

Plug 3 in for x:

  \(\displaystyle f(3)=\frac{(3^{2})+12*3}{3*3}\)

Simplify:

 =  \(\displaystyle \frac{9+36}{9}\)

 = 5

 

Example Question #34 : Algebraic Functions

What is \(\displaystyle f(7)\) of the following equation? 

\(\displaystyle f(x)=x^{2}+15x+35\)

Possible Answers:

\(\displaystyle 190\)

\(\displaystyle 187\)

\(\displaystyle 189\)

\(\displaystyle 188\)

Correct answer:

\(\displaystyle 189\)

Explanation:

To complete an equation with a  function, plug the number inside the parentheses into the equation for \(\displaystyle x\) and solve algebraically.

In this case the \(\displaystyle f(7)=7^{2}+(15*7)+35\)

Square the 7 and multiply to get \(\displaystyle f(7)=49+105+35\)

Add the numbers to get the answer \(\displaystyle f(7)=189\).

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