All SAT Math Resources
Example Questions
Example Question #1 : How To Find X Or Y Intercept
If these three points are on a single line, what is the formula for the line?
(3,3)
(4,7)
(5,11)
y = 4x - 9
y = 5x + 11
y = 3x - 9
y = 4x + 31
y = 3x - 3
y = 4x - 9
Formula for a line: y = mx + b
First find slope from two of the points: (3,3) and (4,7)
m = slope = (y2 – y1) / x2 – x1) = (7-3) / (4-3) = 4 / 1 = 4
Solve for b by plugging m and one set of coordinates into the formula for a line:
y = mx + b
11 = 4 * 5 + b
11 = 20 + b
b = -9
y = 4x - 9
Example Question #1 : X And Y Intercept
The slope of a line is 5/8 and the x-intercept is 16. Which of these points is on the line?
(8,15)
(16, 10)
(0,10)
(32,30)
(32,10)
(32,10)
y = mx + b
x intercept is 16 therefore one coordinate is (16,0)
0 = 5/8 * 16 + b
0 = 10 + b
b = -10
y = 5/8 x – 10
if x = 32
y = 5/8 * 32 – 10 = 20 – 10 = 10
Therefore (32,10)
Example Question #4 : How To Find X Or Y Intercept
A line has the equation: x+y=1.
What is the y-intercept?
0.5
0
1
-1
2
1
x+y=1 can be rearranged into: y=-x+1. Using the point-slope form, we can see that the y-intercept is 1.
Example Question #5 : How To Find X Or Y Intercept
A line has the equation: 2x+4y=8.
What is the x-intercept?
0
-8
4
8
-4
4
To find the x-intercept, rearrange the equation 2x+4y=8 so that x is isolated:
2x=-4y+8
x=-2y+4
Using the point-slope formula, we see that the x-intercept is 4.
Example Question #6 : How To Find X Or Y Intercept
What is the y intercept of the following function of x?
y = 3x
3
1
–3
–1
0
0
The answer is 0 because in slope intercept form, y = mx + b; b is the y intercept. In this case b = 0.
Example Question #3 : How To Find X Or Y Intercept
What is the x-intercept of a line with a slope of 5 and y-intercept of 3.5?
(–3.5, 0)
(0, –0.7)
(0.7, 0)
(–0.7, 0)
(3.5, 0)
(–0.7, 0)
To solve this, first find the equation of our line. The form of the question gives it to us very directly. We can use the slope-intercept form (y = mx + b).
y = 5x + 3.5
The x-intercept is found by setting y = 0, because that will give us the x-value at which the line crosses the x-axis.
0 = 5x + 3.5; –3.5 = 5x; x = –3.5 / 5 or –0.7. The point will be (–0.7, 0)
Example Question #4 : How To Find X Or Y Intercept
Determine the y-intercept of the following line:
The y-intercept occurs when
Example Question #161 : Psat Mathematics
At what point does the graph cross the -axis?
The graph crosses the -axis where . So plugging in and solving yields .
Example Question #162 : Geometry
Find the x-intercepts of .
To find the x-intercepts, plug into the equation and solve for .
Don't forget that there are two solutions, both negative and positive!
Example Question #163 : Geometry
A line with the exquation passes through the point . What is the -intercept?
By plugging in the coordinate, we can figure out that . The -Intercept is when , plugging in 0 for gives us .