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30 votes
30 votes
Line AB passes through (-3,5) and (p, -7), and line CD passes through (3,-1) and (-4,5). For what

value of p, the lines AB and CD are parallel to each other?
Please help me ASPA I NEED THIS BY EVENING

User Randall Ma
by
3.1k points

1 Answer

14 votes
14 votes

Answer:

p = 11

Explanation:

Let's start by finding the slope of line CD:


Slope=(y_2-y_1)/(x_2-x_1)

Plug in the given coordinates into the equation:


Slope=(5-(-1))/(-4-3)=(5+1)/(-7)=-(6)/(7)

Parallel lines have the same slope. This means we can plug the slope of line CD in to find p (in this case p is
x_2)...


Slope=(y_2-y_1)/(x_2-x_1)


-(6)/(7)=(-7-5)/(p-(-3))\\-(6)/(7)=(-12)/(p+3)

Cross multiply (multiply numerator of first fraction by denominator of second and vice versa):


6(p+3)=(-7)(-12)

Distribute:


6p+18=84

Subtract 18 from both sides:


6p=66

Divide both sides by 6


p=11

User TheBlack
by
3.2k points