coordinate geometry

[anindita.dc]

which of the following line is parallel to y=2x+3

A) y=4x+6
B) y=2x-5
c) y=1/2x+3
d) y= -1/2x+5
e) y= -2x-3

In this qs I solved given equation y=2x+3 and get x and y intercept as -3/2 and 0. so given equations which is parallel that must not satisfied by these x and y points. thats way i discard choice A,C,E.
BUT in the case of B AND D both are not satisfied. so how should i get the ans.

please help.

[mkamony]

Hi
To be parallel the 2 lines need to have the same slope. Only B works here.

[jen]

Hi Anindita,

x- and y-intercepts aren't what you're looking for when you're concerned about lines being parallel. Two parallel lines have the same slope -- simple enough. (Also, any line has an infinity of lines that are parallel to it, and those lines will have a wide variety of intercepts!)

Also, you need to know that perpendicular lines have negative reciprocal slopes!

Good luck!

Jen