mx+b form equation help?
find the equation
1.
(2,1) (2,0)
my answer is y=2
but its wrong.help
2.and the mx+b equation
(-2,2) (2,-2)
i have y=-2 and its wrong
(its three blanks to fill 4 the correct asnwer*
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On 1, both points have the same x-coordinate (2) so its equation is x=2 not y=2
On 2, the slope is (-2 – 2)/(2 – -2) = -4/4 = -1
So far it’s y = -1x + b
But replacing x and y with a known point, say (2, -2)
you get -2 = -1(2) + b
-2 = -2 + b
so b = 0
Answer: y = -1x or just y = -x
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Actually, the first equation is x=2. Here’s how. The formula for slope is (Y2-Y1)/(X2-X1). the Xs and Ys stand for the coorinates). Therefore (0-1)/(2-2) is -1/0. Since you cannot divide by 0, the slope of the line is undefined and the equation is X=2 (since it goes through the x-coordinate 2 infinitly).
The second equation:
(-2-2)/ (2-(-2))=-1 The slope is -1. We plug in one of the points into the Y=mx+b form. Let’s choose the first one, (-2, 2) (although the other point would work as well).
2 = (-1)(-2) + b. Solving for “b,” you find that b=0. Therefore, the equation is Y=-1x+0, or more simply, Y=-x. .
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