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41 votes
1) Find the equation of the line that is perpendicular to y=-1/4x - 8 and passes though the point (2,-4).

A) y=4x-12
B) y=4x+4
C) y=1/4x-12
D) y=1/4x+4​

User EEEEH
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2 Answers

12 votes
12 votes

Y=4x - 12

Step-by-step explanation:

y=mx + c

m means gradient

m1 x m2 = - 1

-1/4 x 4 = 4

(your finding the reciprocal)

(x=2, y=-4)

Second line has a gradient of 4, substitute (2,-4) into:

Y = 4x + c

-4 = 4x2 + c

-4 = 8 + c

-8

-12 = c

Thus, y=4x - 12

Hope this helps!

User J Pullar
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2.7k points
19 votes
19 votes

Answer:

y = 4(x) - 12

Step-by-step explanation:


\sf y=-(1)/(4) x -8


\sf Here \ the \ gradient \ is -(1)/(4)


\sf If \ perpendicular: \ \sf -(1)/(m) \rightarrow -(1)/(-(1)/(4)) \rightarrow 4

Find equation of line perpendicular to this line:


\rightarrow \sf y - -4 = 4 ( x -2)


\rightarrow \sf y +4 = 4 x -8


\rightarrow \sf y = 4 x -12

User Kirill Slatin
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2.8k points