Question

which equation represents a line that isperpendicular to a line that has slope -5?
a. -x+5y=-10
b. -5x+y=1/5
c. y=-1/5x+4
d. y-10=5(x+1)

Answer 1

I think it may be "c"

Answer 2

c is close, but somethings awry with it

Answer 3

perp slopes have the property that they they are flipped and negated

Answer 4

-5/1 flips to -1/5 is close; but after negating we get: 1/5

Answer 5

so it would be "a"

Answer 6

a gets me all warm and fuzzy, it has to be a :)

Answer 7

can you explain a reason

Answer 8

sure

given the form: ax+by=c

lets transform this into something we are used to seeing: y = mx + intercept

ax+by=c
-ax -ax
-----------
by = -ax + c ; divide off the b

y = (-a/b) x + (c/b)

since slope is defined conventionally as the letter m in the y=mx .... jargon

m = -a/b

we want -a/b = 1/5