In the xy-plane, a line has slope 3 and x-intercept 3. What is the y-intercept of the line?
1. 9
2. -3
3. 0
4. 3
5. 9
XY plane. Exam pack 2
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Hi prata,
You can deal with this prompt by either drawing a picture or by just creating an equation based on the facts that you know.
The slope-intercept formula for a line is Y = MX + B
From the prompt, we know that the slope is 3 and the X-INTERCEPT is 3 (meaning that X=3 when Y=0)
Y = MX + B
Y = 3X + B
0 = 3(3) + B
0 = 9 + B
-9 = B
So the Y-intercept is -9
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
You can deal with this prompt by either drawing a picture or by just creating an equation based on the facts that you know.
The slope-intercept formula for a line is Y = MX + B
From the prompt, we know that the slope is 3 and the X-INTERCEPT is 3 (meaning that X=3 when Y=0)
Y = MX + B
Y = 3X + B
0 = 3(3) + B
0 = 9 + B
-9 = B
So the Y-intercept is -9
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
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prata wrote:In the xy-plane, a line has slope 3 and x-intercept 3. What is the y-intercept of the line?
1. 9
2. -3
3. 0
4. 3
5. 9
We are given that the line has slope 3 and x-intercept 3 and we need to find its y-intercept. Recall that the slope-intercept form of a line is y = mx + b where m is the slope and b is the y-intercept. Therefore, we need to find the value of b. Since the slope is 3, we know that the line has the form y= 3x + b.
Furthermore, the x-intercept is 3, which means the line passes through the point (3, 0). Thus, we can substitute 3 in for x and 0 for y to find the value of b:
y = 3x + b
0 = 3(3) + b
0 = 9 + b
b = -9
Since the value of b is -9, the y-intercept of the line is -9.
(Note: There is a typo in the choices since both choices 1 and 5 are 9. I think one of them should be -9.)
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slope = m
x-int = -b/m
y-int = b
We've got m = 3 and -b/m = 3. That means that -b/3 = 3, or -b = 9, so b = -9, and we're set!
x-int = -b/m
y-int = b
We've got m = 3 and -b/m = 3. That means that -b/3 = 3, or -b = 9, so b = -9, and we're set!