Question

Which ordered pair represents the y-intercept of the graph of the equation y = -3x - 9?

Answer 1

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Equation
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y = -3x - 9

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Option 1
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If I substitute x = -9, I should get y = 0

When x = -9
y = -3 (-9) - 9
= 18 (I did not get 0, wrong)


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Option 2
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If I substitute x = -3, I should get y = 0
y = -3(-3) - 9
y = 9 - 9 
y = 0 (Yes, I got 0, correct)


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Option 3
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If I substitute x = 0, I should get y = -3
y = -3 (0) - 9
y = 0 - 9
y = -9 (I did not get -3, wrong)


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Option 4
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If I substitute x = 0, I should get y = -9
y = -3 (0) - 9
y = 0 - 9
y = -9 (Yes, I got -9, correct)


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Answer: (-3, 0) and (0, 9) are ordered pairs of the equation (Answer B, D)
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