how to find y-intercepts?

Question

hi i need help on how to find the y-intercept of a line. i used to know how to do this but forgot.
one of the problem question is: find y-intercept of line with points : (-5,2) and (8,2)
i have this so far:
y= -5/13 x + b
if you can re-teach me that would be great.

Answer 1

Simple.

Change the x to be equal to zero. Then solve the equation for y.

The y-intercept would be (0, y)

Your exact problem
calculate slope (which you have incorrect it is not -5/13)
(y1-y2)/(x1-x2) = (2 - 2)/(-5 - 8) = 0 (zero divided by anything except zero is zero)

y-y1 = m(x - x1) Pick either point to do this, I prefer non-negative ones so I'll use (8,2)
y - 2 = 0(x - 8)
y - 2 = 0
y = 2
y-intercept is (0, 2)
This one was easy because it was a horizontal line at y = 2, slope of 0

How about at points (-4,3) (8, 9)
slope (y1-y2)/(x1-x2) = (9 - 3)/(8 - - 4) = 6/12 = 1/2 or 0.5

y - 9 = 1/2(x - 8)
y - 9 = 1/2x - 4
y = 1/2x - 4 + 9
y = 1/2x + 5
set x = 0
y = 1/2(0) + 5
y = 0 + 5
y = 5
y-intercept of (0, 5)

Answer 2

Hmm... anyway to be frank. there will not be any gradient for this line

Gradient of the line = (2-2)/(-5-8)
= 0/-13

The gradient will be 0. Therefore it will not hit the y axis and hence, no y intercepts.


But for example, i give you two coordinates (2,4) and (5,8).

The gradient will be (8-4)/ (5-2) = 4/3
Therefore, using linear equation : y = 4/3x + c (c is the y interception)

Therefore, using one of the coordinates, substitute y = 2 and x = 4 into the equation

Therefore, 2 = 16/3 + c
c (y intercept) = 2 - 16/3
= - 10/3

Therefore the equation of the line : y = 4/3x - 10/3

Answer 3

Well I cant be as detailed at the others but your equation y=-5/13 x+ B is wrong...

First, find the slope of the line. m (slope) is difference of y's over difference of x's...so...

m= (y2-y1) / (x2-x1)
= (2-2)/ (-5 -13)
and the answer is O because the top is 0..that means that the line is a horizontal line.

so your equation so far would be

y=0x+b

to solve for the y intercept, it's the b value...so plug in one of your points...take (2,2)

2=0(2) + B
2= 0 + B
B= 2
so y = 2

(0,2) is your y intercept.

Answer 4

y = mx + c

first you need to find your gradient: m

m = (y2 - y1) / (x2 - x1)
m = (2 - 2) / (8- -5)
m = 0 / 13
m = 0, therefore the gradient of the line is 0.
- This means it is a horizontal straight line.

our y = mx+c equation now looks like this:
y = 0x + c

to find the y-intercept just put any one of the two points back into this equation.

y = 0x + c
(8,2)
2 = 0(8) + c
2 = c, therefore the y-intercept is 2

and our y = mx + c equation now looks like this:
y = 0x + 2
or
y = 2

A horizontal & straight line that passes through y = 2

This method can be used to find the equation for a line when you are provided with any two points.

Hope this helps.

Answer 5

it really is fairly ordinary. at the same time as your equation is in slope intercept style like yours is the coefficient for x, for this reason -4, is your slope. And the consistent dangling on the suitable, for this reason 8, is your y-intercept.

Answer 6

first, find the slope: m=(2-2)/(8+5)=0
after that.. use the point slope form: (y-2)=[0(x+5)]; y-2=0; y=2
automatically, your y-intercept is 2 or (0,2)

Answer 7

on y axis all the points are in the form (0,y)

Hence put 0 for x in the equation.
find y
that is all

the slope (2-2)/(8-(-5))= 0
y-y1=m(x-x1)
y-2=0 (x-8)
y=2

y-intercept (0,2)

Answer 8

(-5,2) and (8,2)
m = (2 - 2)/(8 - (-5))
m = 0/(8 + 5)
m = 0/13
m = 0

(-5,2), m = 0
2 = 0(-5) + b
2 = 0 + b
b = 2

ANS : b = 2

Answer 9

horizontal line passing throuh (0,2)

hence y-intercept is 2