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Find a value for C that will give the following system no solution:
3x-2y=3
6x+cy=4

User Dicemaster
by
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1 Answer

4 votes

Answer:

c = - 4

Explanation:

Nothing else matters except that the number associated with the y value in equation one = 1 and the number in front of x is known in equation 1. Then we'll get around to looking at c

Add 2y to both sides of equation 1 (the top equation)

3x - 2y + 2y = 3 + 2y

3x = 2y + 3

Now divide both sides of the equation by 2

3x/2 = y + 3/2

What's in front of x? It is (3/2)

So divide both sides of 6x + cy = 4 by c

6x/c + y = 4/c

Now put 6x/c on the right hand side so y is by itself.

y = -6x/c + 4/c

What do you have to do now?

You must equate -6x/c = 3/2x

Why?

The slopes have to be the same so the lines are parallel and never cross. That will give no solutions.

-6x/c = 3x / 2 Divide both sides by x

-6/c = 3/2 Cross multiply

3c = - 6 * 2 Combine

3c = - 12 Divide by 3

c = - 12/3

c = - 4

User Aetheus
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