Question

For the function rule y=-2x-3, provide the x-y coordinates of the y-intercept and x-intercept.

Answer 1

x-intercept:

Plug in y = 0 and solve for x

y=-2x-3

0=-2x-3

...Tell me what you get

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y-intercept

Plug in x = 0 and evaluate to find y

y=-2x-3

y=-2(0)-3

...and tell me what you get here

Answer 2

i dont understand it

Answer 3

Do you know how to solve 0=-2x-3 for x?

Answer 4

no

Answer 5

Alright, I'll walk you through it

0=-2x-3

0+3=-2x-3+3 ... Add 3 to both sides

3 = -2x ... Notice how -3+3 = 0 (and goes away)

3/(-2) = (-2x)/(-2) ... Divide both sides by -2

-3/2 = x ... The -2 terms on the right side divide and cancel (and go away)

x = -3/2 ... Flip the equation

So when y = 0, x is x = -3/2


So the x-intercept is \(\Large \left(-\frac{3}{2},0\right)\)


Does that make sense?

Answer 6

Yes

Answer 7

ok great

Answer 8

Can you tell me what y=-2(0)-3 becomes ?

Answer 9

-1?

Answer 10

close

Answer 11

y=-2(0)-3

y=0-3 .... negative 2 times zero is zero

y = -3 ... subtract


So y=-2(0)-3 becomes y = -3

Answer 12

This means that when x = 0, y is y = -3

Answer 13

So the y-intercept is \(\Large \left(0,-3\right)\)

Answer 14

OHHH ok now i see

Answer 15

that's great

Answer 16

Now what about the x intercept?

Answer 17

Look a few posts above and you'll see the work, but the x-intercept again is \(\Large \left(-\frac{3}{2},0\right)\)

Answer 18

ok sorry i looked past it

Answer 19

that's ok

Answer 20

Thanks

Answer 21

you're welcome