MathRevolution wrote:
Which of the following lines has x-intercept and y-intercept that are integers?
A. y=3x+1
B. y=√x+1
C. y=-2/x
D. y=x^2-1
E. xy=1
*An answer will be posted in 2 days.
IMPORTANT POINT #1: The y-intercept is the point where the x-coordinate is
0So, let's plug x =
0 into each answer choice.
We get:
A. y= 3(
0) + 1 = 1. Integer - KEEP
B. y = √
0 + 1 = 1. Integer - KEEP
C. y = -2/
0 undefined. ELIMINATE
D. y =
0² - 1 = -1. Integer - KEEP
E. (
0)y = 1. When we solve for y, y is undefined. ELIMINATE
We're left with A, B and D
IMPORTANT POINT #2: The x-intercept is the point where the y-coordinate is
0So, let's plug y =
0 into each answer choice.
We get:
A.
0 = 3x + 1 Solve to get x = -1/3. Not an integer. ELIMINATE
B.
0 = √x + 1 Unsolvable for x. ELIMINATE
D.
0 = x² - 1 x = 1 or -1, Both are integers. KEEP!
Answer: D
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