8. Find the x and y intercepts of y = 3x + 4?

Question

(3,0) (0,4)
(4/3,0) (0,4)
(-4/3,0) (0,4)
(4,0) (0,3)

Answer 1

x-intercept is when y=0...

so y = 3x + 4.... becomes...

0 = 3x + 4.... now solve for x...

3x = -4....

so x = -4/3...

the only choice that has -4/3 as the x-value coordinate is choice C. (-4/3, 0) .... so you don't even have to continue to find the y-intercept because you already have it in the answer! y-intercept is (0,4 ) =)

If you want to check if it works, just plug x = 0 and y = 4 into the given equation... to see if it is true...

y = 3x + 4 becomes...

4 = 3(0) + 4 ... Is that true?

4 = 0 + 4...

4 = 4... Yes... the statement is true...

Hope this helped!

Answer 2

To find the x intercept you plug in zero for y and solve for x--
0 = 3x + 4, 3x = -4, x = -4/3. Because it is an x intercept, the y value will be 0, so the coordinates are (-4/3, 0).
With a multiple choice question, you can rule out all of those other options, because there is only one that includes this as an x coordinate, but just in case, I'll finish.
Next you plug in zero for x and since the equation is in slope-intercept form it is already solved for y--
y = 3(0) + 4 = 4, and the x coordinate is 0, so (0, 4).

Good luck!

Answer 3

First, simplify it to slop intercept variety y = 8/4 -3x/4 = 2 - (3/4)x = (-3/4)x + 2 so the situation y = mx + b and m = slope and b = y-intercept slope = (-3/4) y-intercept = 2 and for c, plug in 8 for x y = (-3/4)(8) + 2 = -4

Answer 4

Just substitute the coordinates in for X and Y.

1a) (3,0) 0 = 3(3) + 4 doesn't work 13 doesn't = 0
1b) (0,4) 4 = 3(0) + 4 works 4 = 4

2a) (4/3,0) 0 = 3(4/3) + 4 doesn't work 8 doesn't equal 0

and so on

Answer 5

y intercept: (0,4). (Set x = 0 and solve for y)
x intercept. Set y = 0 and solve for x:
0 = 3x+4
3x = -4
x = -4/3.
Your third choice is right.

Answer 6

set y=0
0=3x+4
-4 -4
-4=3x
-4/3=3x/3
-4/3=x

set x=0
y=3(0)+4
y=4


so.....(-4/3,0) and (0,4)