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If 3c + 2d = 8 and c < –1, which one of the following could
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22 Jul 2019, 02:49
22 Jul 2019, 02:49
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If 3c + 2d = 8 and c < –1, which one of the following could be a value for d?
(A) 2.5
(B) 3.5
(C) 4.5
(D) 5.5
(E) 6.5
(A) 2.5
(B) 3.5
(C) 4.5
(D) 5.5
(E) 6.5
Re: If 3c + 2d = 8 and c < –1, which one of the following could
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22 Jul 2019, 09:33
22 Jul 2019, 09:33
1
We should start by getting our equation in terms of d.
3c + 2d = 8
2d = 8 - 3c
d = 4 - 1.5(c)
We can now consider what happens at the boundary condition for c. Let's plug in c = -1 and see what happens.
d = 4 - 1.5(-1)
d = 5.5
However, c must be smaller than -1. Since we're subtracting a negative number, we know that the smaller c gets, the larger d will get. This means that d must be at least a little bigger than 5.5. Only E satisfies that requirement.
3c + 2d = 8
2d = 8 - 3c
d = 4 - 1.5(c)
We can now consider what happens at the boundary condition for c. Let's plug in c = -1 and see what happens.
d = 4 - 1.5(-1)
d = 5.5
However, c must be smaller than -1. Since we're subtracting a negative number, we know that the smaller c gets, the larger d will get. This means that d must be at least a little bigger than 5.5. Only E satisfies that requirement.
Re: If 3c + 2d = 8 and c < –1, which one of the following could
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14 Sep 2020, 23:57
14 Sep 2020, 23:57
jwolbrum wrote:
We should start by getting our equation in terms of d.
3c + 2d = 8
2d = 8 - 3c
d = 4 - 1.5(c)
We can now consider what happens at the boundary condition for c. Let's plug in c = -1 and see what happens.
d = 4 - 1.5(-1)
d = 5.5
However, c must be smaller than -1. Since we're subtracting a negative number, we know that the smaller c gets, the larger d will get. This means that d must be at least a little bigger than 5.5. Only E satisfies that requirement.
3c + 2d = 8
2d = 8 - 3c
d = 4 - 1.5(c)
We can now consider what happens at the boundary condition for c. Let's plug in c = -1 and see what happens.
d = 4 - 1.5(-1)
d = 5.5
However, c must be smaller than -1. Since we're subtracting a negative number, we know that the smaller c gets, the larger d will get. This means that d must be at least a little bigger than 5.5. Only E satisfies that requirement.
How can we substitute C with -1? Its stated C < -1 so c ideally should be anything above C = -1.0001 at least. Can this be explained?
