Question

Need help with Graphing in Algebra


Which of the following is not true about the equation
y-7=-2(x+1)

A. The slope is -2
B. It passes through the point (-1,7)
C. It is the same line as y=-2x+5
D. It is perpendicular to y=1/2x-7

Answer 1

C

Answer 2

But I could also be B couldn't it?

Answer 3

Please I need a answer and explanation

Answer 4

if you rearrange it to y =
it should be easier to see

Answer 5

@09chunga I already did and I still can't figure it out
Y=-2X-9

Answer 6

so this means that A is true for that question because -2 is the gradient, so it cant be this.
B, you can find whether its true or false by substituting the x value to see if you get the y value.

Answer 7

I know it's not A but that's as far as I can narrow it down @09chunga

Answer 8

It could be B but couldn't it be c too?

Answer 9

so for B: you sub x=-1 into the equation you rearranged: y=-2x-9 and if you get 7, it means its true

Answer 10

You don't get seven you get negative 7

Answer 11

for C, its clear that y=-2x-9 and y=-2x+5 is definitely not the same thing

Answer 12

THEN WHICH ONE IS IT

Answer 13

calm down.. it could be B or C... unless when they say "the same" they meant that its parallel?

Answer 14

if they mean y=-2x+5 is parallel to that, then the answer would be B. because B is definitely not correct.

Answer 15

And is d perpemdicular I can't tell because my calculator screen stretches the graph

Answer 16

Perpendicular*

Answer 17

D should be true because,
eg. gradient 2, perpendicular is -1/2
gradient 3/4, perpendicular is -4/3
when the gradient of this and the gradient of perpendicular is multiplied tog. it = -1

Answer 18

But it's not a right angle to it though

Answer 19

it should be, maybe your cal screen is not accurate, the rule is
gradient x gradient of perpendicular line = -1

Answer 20

Wait

Answer 21

-2* -1/2 = 1 not -1

Answer 22

It's wrong

Answer 23

in the question above, it says 1/2 not -1/2

Answer 24

My fault then on paper it's negative completely sorry

Answer 25

It's a typo

Answer 26

ohh i see

Answer 27

are you allowed to choose more than 1 answer? because in this case, all BCD is wrong..

Answer 28

@09chunga Sorry for not responding I needed to do chores and I will talk to my teacher about this, Thanks For Helping

Answer 29

no prob, wasnt much help tho... D:

Answer 30

You really were because all I wanted was conformation that I wasn't going crazy