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4 votes
How many solution does this line system have y= 2x -5. -8x -4y=-20

1 Answer

3 votes
Remark
If you try graphing this, you will get either 0, 1 or an infinite number. I always graph a question to get the answer first.

The graph is below.

So it looks like we are looking for 1 solution

Step One
Convert the second equation to a slope intercept.
-8x - 4y = - 20 Add 8x to both sides.
-4y = 8x - 20 Divide by - 4
y = 8x/-4 - 20/-4
y= -2x + 5

Step Two
equate the two equations right hand sides.
-2x + 5 = 2x - 5 Add 2x to both sides.
5 = 2x + 2x - 5 combine like terms on the right.
5 = 4x - 5 Add 5 to both sides.
10 = 4x Divide by 4
x = 10/4
x = 2.5

Step 3
Solve for y
y = 2x - 5
y = 2*2.5 - 5
y = 0

Solution (2.5, 0 )<<<<<< Answer
If there are choices, please list them.


How many solution does this line system have y= 2x -5. -8x -4y=-20-example-1
User Taytay
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