SAT II Math I : Properties of Functions and Graphs

Study concepts, example questions & explanations for SAT II Math I

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Example Questions

Example Question #1 : Slope

What is the slope of the following equation?  \displaystyle 2y = 3-7x

Possible Answers:

\displaystyle 3

\displaystyle 14

\displaystyle -14

\displaystyle -\frac{7}{2}

\displaystyle \frac{3}{2}

Correct answer:

\displaystyle -\frac{7}{2}

Explanation:

The given equation will need to be rewritten in slope intercept format.

\displaystyle y=mx+b

Divide by two on both sides.

\displaystyle \frac{2y }{2}=\frac{ 3-7x}{2}

Rearrange the right side by order of powers.

\displaystyle y= -\frac{7}{2}x+\frac{3}{2}

The slope can be seen as \displaystyle -\frac{7}{2}

The answer is:  \displaystyle -\frac{7}{2}

Example Question #41 : Functions And Graphs

What is the slope of the given equation?  \displaystyle y=-\frac{1}{2x}+3

Possible Answers:

\displaystyle 2

\displaystyle 3

\displaystyle -2

\displaystyle -\frac{1}{2}

Correct answer:

Explanation:

The slope in a linear equation is defined as \displaystyle y=mx+b.

The x-variable exists in the denominator, which refers to the parent function of:

\displaystyle y=\frac{1}{x}

This function is not linear, and will have changing slope along its domain.

The answer is:  

Example Question #1 : Maximum And Minimum

What is the vertex of the following function? Is it a maximum or a minimum?

\displaystyle \small f(x) = -3(x-2)^2+9

Possible Answers:

\displaystyle \small (-2,9); minimum

\displaystyle \small (2,9); minimum

\displaystyle \small (-2,9); maximum

\displaystyle \small \small (2,9); maximum

\displaystyle \small (2,-9); maximum

Correct answer:

\displaystyle \small \small (2,9); maximum

Explanation:

The equation of a parabola can be written in vertex form

\displaystyle \small f(x) = a(x-h)^2+k

where \displaystyle \small \tiny (h,k) is the vertex and \displaystyle \tiny a determines if it is a minimum or maximum. If \displaystyle \tiny a is positive, then it is a minimum; if \displaystyle \tiny a is negative, then it is a maximum.

\displaystyle \small \small f(x)=-3(x-2)^2+9

In this example, \displaystyle \small \small a is negative, so the vertex is a maximum.

\displaystyle \small h = 2 and \displaystyle \small k=9

\displaystyle \small (h,k)=(2,9)

 

 

Example Question #1 : Maximum And Minimum

Determine the maximum or minimum of \displaystyle y=6-9x^2+6x.

Possible Answers:

Correct answer:

Explanation:

Rewrite the equation by the order of powers.

\displaystyle y=-9x^2+6x+6

This is a parabola in standard form:  \displaystyle y=ax^2+bx+c

Determine the values of \displaystyle a, b to the vertex formula.

\displaystyle x=-\frac{b}{2a}=-\frac{6}{2(-9)}= \frac{6}{18}=\frac{1}{3}

Since the leading coefficient of the parabola is negative, the parabola will curve downward and will have a maximum point.  

Therefore there is a maximum at,

 \displaystyle x=\frac{1}{3}.

 

 

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