All ACT Math Resources
Example Questions
Example Question #1 : X And Y Intercept
Find the slope of the following line: 6x – 4y = 10
5/2
1.5
–1.5
–5/2
1.5
Putting the equation in y = mx + b form we obtain y = 1.5x – 2.5.
The slope is 1.5.
Example Question #142 : Coordinate Plane
What is the x-intercept of the line in the standard coordinate plane for the following equation?
12
-24
2
3
2
This question is asking us to find the x-intercept. Remember that the y-value is equal to zero at the x-intercept. Substitute zero in for the y-variable in the equation and solve for the x-variable.
Add 2 to both sides of the equation.
Divide both sides of the equation by 6.
The line crosses the x-axis at 2.
Example Question #2 : X And Y Intercept
What is the equation of a line that has an x-intercept of 4 and a y-intercept of -6?
The equation of a line can be written in the following form:
In this formula, m is the slope, and b represents the y-intercept. The problem provides the y-intercept; therefore, we know the following information:
We can calculate the slope of the line, because if any two points on the function are known, then the slope can be calculated. Generically, the slope of a line is defined as the function's rise over run, or more technically, the changes in the y-values over the changes in the x-values. It is formally written as the following equation:
The problem provides the two intercepts of the line, which can be written as and . Substitute these points into the equation for slope and solve:
.
Substitute the calculated values into the general equation of a line to get the correct answer:
.
Example Question #1 : How To Find X Or Y Intercept
What are the y and x intercepts of the given equation, respectively?
y = 2x – 2
(0, –2), (1, 0)
(0, 0), (0, 0)
(0, –2), (2, 0)
(0, –2), (–2, 0)
(0, 2), (2, 0)
(0, –2), (1, 0)
The equation is already in slope-intercept form. The y-intercept is (0, –2). Plug in 0 for y and we get the x intercept of (1, 0)
Example Question #1 : How To Find X Or Y Intercept
What is the x-intercept of the following line?
y = –3x + 12
–4
–1/4
1/4
2
4
4
The x-intercept occurs when the y-coordinate = 0.
y = –3x + 12
0 = –3x + 12
3x = 12
x = 12/3 = 4
Example Question #1 : X And Y Intercept
What is the -coordinate of the point in the standard coordinate plane at which the two lines and intersect?
Example Question #2 : X And Y Intercept
What is the -intercept of the line in the standard coordinate plane that goes through the points and ?
The answer is .
The slope of the line is determined by calculating the change in over the change in .
The point-slope form of the equation for the line is then
. The -intercept is determined by setting and solving for . This simplifies to which shows that is the -interecept.
Example Question #1 : How To Find X Or Y Intercept
What are the and -intercepts of the line defined by the equation:
To find the intercepts of a line, we must set the and values equal to zero and then solve.
Example Question #2 : How To Find X Or Y Intercept
In the standard (x, y) coordinate plane, a circle has the equation . At what points does the circle intersect the x-axis?
The generic equation of a circle is (x - x0)2 + (y - y0)2 = r2, where (x0, y0) are the coordinates of the center and r is the radius.
In this case, the circle is centered at the origin with a radius of 8. Therefore the circle hits all points that are a distance of 8 from the origin, which results in coordinates of (8,0) and (-8,0) on the x-axis.
Example Question #3 : How To Find X Or Y Intercept
What is the y-intercept of a line that passes through the point with slope of ?
Point-slope form follows the format y - y1 = m(x - x1).
Using the given point and slope, we can use this formula to get the equation y - 8 = -2(x + 5).
From here, we can find the y-intercept by setting x equal to zero and solving.
y - 8 = -2(0 + 5)
y - 8 = -2(5) = -10
y = -2
Our y-intercept will be (0,-2).
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