Question

Write an equation of a line perpendicular to y=1/2x-5 in slope-intercept form that passes through the points (2,-7).
A.) y=1/2x-7
B.) y=2x+2
C.) y=-2x-5
D.) y=-2x-3

Answer 1

Please explain to!(:

Answer 2

ok... there r some basic things u need to know first...
if there r 2 lines which r perpendicular to each other...
lets say the slope of one line is "m"
then the slope of the other line is "(-1/m)

for an example
if the slope of line is "4"
then the slope of the line perpendicular to it is "(-1/4)"

so... first of all
what is the slope of
y=1/2x-5 ?

can u find it ?

Answer 3

1/2?

Answer 4

yep... so what will be the slope of a line perpendicular to it ?

Answer 5

-1/1/2?

Answer 6

yep... now if u simplify it u will get -2.. got it ?

Answer 7

yes

Answer 8

and now...
the general format of a straight line is
y = mx + b
where
m = slope
b = y - intercept..

we already know the slope of the line we want .. so we can write it as
y= -2x + b
now all we have to do is find b

to do that we can use the given pair of coordinates (2 , -7)
since the line pass through this point...
we can plug these values in to our equation..

in ( 2 , -7)
x value = 2
y value = -7

so... if we plug them
y = -2x + b
-7 = -2(2) + b

what will u get for b ?

Answer 9

- 7 = -4 + b
b = -7 + 4
= -3

so... the equation of the line will be
y = -2x - 3
hope this will help ya :)

Answer 10

it helped a lot! thank you so much!