Write the equation in the form Ax + By = C. Find an equation of a line passing through the pair of points (-7,3) and (-8,-9).
1 answer:
Answer:
12x -y = -87
Step-by-step explanation:
You can start with the 2-point form of the equation of a line and manipulate it to give you the standard form.
y = (y2 -y1)/(x2 -x1)(x -x1) +y1
y = (-9 -3)/(-8 -(-7))(x -(-7)) +3
y = (-12/-1)(x +7) +3
y = 12x +84 +3
-12x +y = 87 . . . . . subtract the x-term
12x -y = -87 . . . . . . make the leading coefficient positive (per standard form)
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Assuming we're dealing with , which is the same as writing (x+2)/(-5) < 4, then the answer is choice C.
We multiply both sides by -5 and this will flip the inequality sign.
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Multiplying or dividing both sides by a negative number flips the inequality sign.
An example would be saying -2x < 10 leads to x > -5
What we can do is divide both sides by -2 and flip the inequality sign, or we could follow the steps shown below
- -2x < 10
- 0 < 10+2x ... adding 2x to both sides
- -10 < 2x ... subtracting 10 from both sides; this is one way to see why the sign flip happens
- 2x > -10
- x > -10/2 ..... dividing both sides by 2
- x > -5