Question

True or False. The following two lines are perpendicular.

y = -x - 7

y + x = 20

Answer 1

to know whether the lines are perpendicular or not,
first thing to consider are their respective slope
remember that a line perpendicular to the other is having a slope that is negative reciprocal of the other
say line 1: m=1/2
line 2: m= -2

Answer 2

okay

Answer 3

slope-intercept form:
y=mx + b
where m is the slope and b is the y-intercept

Answer 4

okay now what do you do?

Answer 5

for the first line, notice that it's already in the y-intercept form:
y = -x - 7
that line is having slope as? m=?

Answer 6

m=-x?

Answer 7

or 1/2?

Answer 8

-1/2?

Answer 9

m = -1
now try to get the slope of the second line by transposing x to the right

Answer 10

m is the value of the coefficient of x

Answer 11

so x for the second one would be 1?

Answer 12

you still need to have it in y-intercept form for you to identify the slope
have it this way:
y + x = 20
since the slope-intercept form is y=mx + b then
subtract x from both sides of the equation
y + x - x = -x + 20
y = -x + 20
what's the slope then?

Answer 13

-1?

Answer 14

yep.
you have the slopes of the two lines as -1 and -1 respectively.
is -1 the negative reciprocal of -1?

Answer 15

yes?

Answer 16

nope. the negative reciprocal of -1 is 1. they are parallel lines since they are having the same slope.. lines having the same slope are parallel lines. they never meet no matter how long you extend

Answer 17

okay... thanks... wanna help me with another?

Answer 18

yw :)

Answer 19

go ahead

Answer 20

True or False. The following two lines are parallel.

y = 2x + 5

y = -2x