linear functions-equations and graphs

spoiled

New member
Joined
Nov 19, 2007
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2
This is one thing that confuses me so much that I can't even think straight. There is this one question that i really don't get.

Which of the folowing equations describes a line perpendicular to the line y=7x+49?

A- y= -7x-49
B- y= -1/7x+10
C- y= 1/7x+7
D- y=7x-49
E- y=7x+14

Please help!!!!
 

Mrspi

Senior Member
Joined
Dec 17, 2005
Messages
2,128
spoiled said:
This is one thing that confuses me so much that I can't even think straight. There is this one question that i really don't get.

Which of the folowing equations describes a line perpendicular to the line y=7x+49?

A- y= -7x-49
B- y= -1/7x+10
C- y= 1/7x+7
D- y=7x-49
E- y=7x+14

Please help!!!!
This isn't really a calculator question.

The equation you are given,

y = 7x + 49

is in "slope-intercept form," y = mx + b.

When the equation of a line is in this form, the coefficient of x (represented by "m" in the equation) is the slope of the line.

Now....you are expected to know that if two lines are perpendicular, the slopes of those lines are "opposite reciprocals."

What is the slope of the given line? It is 7. What is the opposite reciprocal of 7? It is -1/7.

Now, look at the answer choices. Does one of them have a slope of -1/7?

I hope this helps you.
 

spoiled

New member
Joined
Nov 19, 2007
Messages
2
Thanks
 
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