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If (a, -5) is a point on the graph of y = x^2 + 6x, what is a?
Let me see.
Let y = -5
Let x = a
-5 = a^2 + 6a
a^2 + 6a + 5 = 0
Factor.
(a + 1) (x + 5) = 0
a + 1 = 0
a = -1
a + 5 = 0
a = -5
I got two values for a. Which one is right? Are they both right?
You say?
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If (a, -5) is a point on the graph of y = x^2 + 6x, what is a?
-5 = a^2 + 6a
a^2 + 6a + 5 = 0
(a + 1) (x + 5) = 0
a = -1
a = -5
I got two values for a. Which one is right? Are they both right?
quadratics usually have 2 sol'ns
to check your ans plug it back into the problme
what does (-1)^2 + 6(-1) equal
what does (-5)^2 + 6(-5) equal
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harpazo1965 wrote:If (a, -5) is a point on the graph of y = x^2 + 6x, what is a?
-5 = a^2 + 6a
a^2 + 6a + 5 = 0
(a + 1) (x + 5) = 0
a = -1
a = -5
I got two values for a. Which one is right? Are they both right?
quadratics usually have 2 sol'ns
to check your ans plug it back into the problme
what does (-1)^2 + 6(-1) equal
what does (-5)^2 + 6(-5) equal
(-1)^2 + 6(-1) = (1) - 6 = -5
(-5)^2 + 6(-5) = (25) - 30 = - 5
The correct of a is -5.
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(-1)^2 + 6(-1) = (1) - 6 = -5
(-5)^2 + 6(-5) = (25) - 30 = - 5
The correct of a is -5.
why do you say a = -1 is not a sol'n?
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harpazo1965 wrote:(-1)^2 + 6(-1) = (1) - 6 = -5
(-5)^2 + 6(-5) = (25) - 30 = - 5
The correct of a is -5.
why do you say a = -1 is not a sol'n?
Why? I was rushing through the math work.
Answers: a = -5, a = -1
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