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For what value of a and b will the system of equations below have infinite solutions?

5x - y = 8
20x + ay = b

User Buddhi
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1 Answer

4 votes

Answer:

Explanation:

For a system of equations to have infinite solutions, the two equations must represent the same line or be proportional to each other.

Let's consider the first equation:

1. 5x - y = 8

Now, we'll rewrite the second equation in terms of a and b:

2. 20x + ay = b

To determine the values of a and b that make these equations equivalent, we can rewrite equation 2 by isolating the variable y:

2.1. ay = -20x + b

2.2. y = (-20/a)x + (b/a)

Now, we can see that for the system to have infinite solutions, the slopes of both equations must be equal. This means that the coefficient of x in equation 1 (which is 5) must be equal to the coefficient of x in equation 2.1 (which is -20/a). Therefore:

5 = -20/a

To solve for a:

a = -20/5

a = -4

Now that we've determined the value of a, let's focus on making the y-intercepts match as well. In equation 1, the y-intercept is 8 (i.e., when x = 0, y = 8). In equation 2.2, the y-intercept is b/a.

For the system to have infinite solutions, these y-intercepts must be equal:

8 = b/a

To solve for b:

b = 8a

Now, since we already found that a = -4, we can determine the value of b:

b = 8 * (-4)

b = -32

So, for the system of equations to have infinite solutions, a must be equal to -4, and b must be equal to -32.

User Randall Helms
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