All SAT Math Resources
Example Questions
Example Question #4 : Graphing
Below is the graph of the function :
Which of the following could be the equation for ?
First, because the graph consists of pieces that are straight lines, the function must include an absolute value, whose functions usually have a distinctive "V" shape. Thus, we can eliminate f(x) = x2 – 4x + 3 from our choices. Furthermore, functions with x2 terms are curved parabolas, and do not have straight line segments. This means that f(x) = |x2 – 4x| – 3 is not the correct choice.
Next, let's examine f(x) = |2x – 6|. Because this function consists of an abolute value by itself, its graph will not have any negative values. An absolute value by itself will only yield non-negative numbers. Therefore, because the graph dips below the x-axis (which means f(x) has negative values), f(x) = |2x – 6| cannot be the correct answer.
Next, we can analyze f(x) = |x – 1| – 2. Let's allow x to equal 1 and see what value we would obtain from f(1).
f(1) = | 1 – 1 | – 2 = 0 – 2 = –2
However, the graph above shows that f(1) = –4. As a result, f(x) = |x – 1| – 2 cannot be the correct equation for the function.
By process of elimination, the answer must be f(x) = |2x – 2| – 4. We can verify this by plugging in several values of x into this equation. For example f(1) = |2 – 2| – 4 = –4, which corresponds to the point (1, –4) on the graph above. Likewise, if we plug 3 or –1 into the equation f(x) = |2x – 2| – 4, we obtain zero, meaning that the graph should cross the x-axis at 3 and –1. According to the graph above, this is exactly what happens.
The answer is f(x) = |2x – 2| – 4.
Example Question #5 : Graphing
What is the equation for the line pictured above?
A line has the equation
where is the intercept and is the slope.
The intercept can be found by noting the point where the line and the y-axis cross, in this case, at so .
The slope can be found by selecting two points, for example, the y-intercept and the next point over that crosses an even point, for example, .
Now applying the slope formula,
which yields .
Therefore the equation of the line becomes:
Example Question #1 : Graphing
Which of the following graphs represents the y-intercept of this function?
Graphically, the y-intercept is the point at which the graph touches the y-axis. Algebraically, it is the value of when .
Here, we are given the function . In order to calculate the y-intercept, set equal to zero and solve for .
So the y-intercept is at .
Example Question #5 : Graphing
Which of the following graphs represents the x-intercept of this function?
Graphically, the x-intercept is the point at which the graph touches the x-axis. Algebraically, it is the value of for which .
Here, we are given the function . In order to calculate the x-intercept, set equal to zero and solve for .
So the x-intercept is at .
Example Question #7 : Graphing
Which of the following represents ?
A line is defined by any two points on the line. It is frequently simplest to calculate two points by substituting zero for x and solving for y, and by substituting zero for y and solving for x.
Let . Then
So our first set of points (which is also the y-intercept) is
Let . Then
So our second set of points (which is also the x-intercept) is .
Example Question #6 : Graphing
The graphic shows Bob's walk. At what times is Bob the furthest from home?
to
to
to
If we look at the graph, the line segment from to , is the furthest from home. So the answer will be from to .
Example Question #1 : Graphing
On the coordinate plane, a triangle has its vertices at the points with coordinates
, , and . Give the coordinates of the center of the circle that circumscribes this triangle.
The referenced figure is below.
The two non-horizontal line segments are perpendicular, as is proved as follows:
The slope of the line that connects and can be found using the slope formula, setting :
The slope of the line that connects and can be found similarly, setting :
The product of their slopes is , which indicates perpendicularity between the sides.
This makes the triangle right, and the side with endpoints and the hypotenuse. The center of the circle that circumscribes a right triangle is the midpoint of its hypotenuse, which is easily be seen to be the origin, .
Example Question #11 : Graphing
On the coordinate plane, a triangle has its vertices at the points with coordinates , , and . Give the coordinates of the center of the circle that circumscribes this triangle.
The referenced figure is below.
The triangle formed is a right triangle whose hypotenuse is the segment with the endpoints and . The center of the circle that circumscribes a right triangle is the midpoint of its hypotenuse, so the midpoint formula
can be applied, setting :
The midpoint of the hypotenuse, and, consequently, the center of the circumscribed circle, is the point with coordinates .
Example Question #271 : Coordinate Geometry
On the coordinate plane, , , and are the points with coordinates , , and , respectively. Lines , , and are the perpendicular bisectors of , , and , respectively.
and intersect at a point ; and intersect at a point ; and intersect at a point .
Which of these statements is true of , , and ?
and are the same point; is a different point.
, , and are distinct and collinear.
, , and are distinct and are the vertices of a triangle similar to .
, , and are the same point.
, , and are distinct and are the vertices of an equilateral triangle.
, , and are the same point.
Another way of viewing this problem is to note that the three given vertices form a triangle whose sides' perpendicular bisectors intersect at the points , , and . However, the three perpendicular bisectors of the sides of any triangle always intersect at a common point. The correct response is that , , and are the same point.
Example Question #655 : Geometry
Figure NOT drawn to scale.
On the coordinate axes shown above, the shaded triangle has area 40.
Evaluate .
The length of the horizontal leg of the triangle is the distance from the origin to , which is 8.
The area of a right triangle is half the product of the lengths of its legs and , so, setting and and solving for :
Therefore, the length of the vertical leg is 10, and, since the -intercept of the line containing the hypotenuse is on the positive -axis, this intercept is . The slope of a line with intercepts is
,
so, setting and :
Set and in the slope-intercept form of the equation of a line,
;
the line has equation
The -coordinate of the point on the line with -coordinate 2 can be found using substitution; setting ::