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Solve the equation by graphing -3x+1=-8

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Treat this problem as one involving finding the point at which two lines intersect.

One line would be y = -3x + 1; the other would be the horiz. line y = -8.

Whenever two lines intersect, the coefficients of the point of intersection satisfy both equations. Thus, we set y = y, or, in this case, -3x + 1 = -8.

Subtracting 1 from both sides, we get -3x + 1 - 1 = -8 - 1, or

-3x = -9, or (after dividing both lines by -3) x = 3.

We already know that the y-coordinate of the point of intersection / solution is y = -8, so we can write the solution as

(3, -8)

First, draw the horizontal line y = -8.

Next, draw the line y = -3x + 1. Letting x = 0, we get y = 1, which means that the y-intercept is (0,1). Place a black dot at (0,1). Now, taking info from the slope (-3), find and place a black dot at the next point, as follows:

From your dot at (0,1), move 1 unit to the right and then 3 units down. This point will be (1,-3). Place a black dot there.

Draw a line through your two black dots. You'll see that this line and the line y = -8 intersect at (3,-8).

User Nodebase
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7.7k points
3 votes
subtract both sides by 1 and you will get

-3x=-9

divided both sides by -3

and you will get x= 3

multiplying or dividing integers :when the signs are the same it is a positive and when they are different it is a negative
User Jney
by
8.5k points

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