Algebra One?

Question

Determine the y-intercept of the graph: -3x - 5y =15

Answer 1

y-intercept is when x=0
so -5y = 15
or y = -3

Answer 2

People seem to give answers, but seem disinclined to explain how they came up with them...

"Y-Intercept" that is the y-value of point (x,y) at which a line crosses the Y-Axis. There is two ways to figure that out...

First, what is the value of x anywhere on the y axis? Look at the Cartesian coordinates. Hint: it's half way between -1 and 1. So if you set x to that value and solve for y, you have the Y-intercept.

Second, there is a form of a linear equation (equation for a straight line) called the "Slope-Intercept" form. y=mx+b where "m" is the slope, and "b" is the Y-intercept. Math teachers, and authors of math books, seem to think it's great fun giving you linear equations that are not in Slope-Intercept form and asking questions about the slope and intercept. All you have to do is solve for y... that is, get y on one side of the equation all by itself and everything else on the other. Here's how...
Suppose you are given something that looks like ax+by+c=d
(1) Add -c to both sides...
ax+by=d-c

(2) Add -ax to both sides...
by = d - c - ax

(3) Multiply both sides by 1/b
y = (-a/b)x + (d-c)/b

Done! -a/b is the slope, and (d-c)/b is the intercept.


DO NOT MEMORIZE "y = (-a/b)x + (d-c)/b." It's just one more useless thing to remember. Rather, learn the "slope-intercept" form of a linear equation and how to solve an equation to get it.
You can learn a lot from the slope-intercept form. If you have more than one line, you can tell if they are parallel or not. If they're not parallel, you can tell whether they are perpendicular or not.

Answer 3

Hey there!

Here's the answer.

-3x-5y=15 --> Write the problem.
-5y=15+3x --> Add 3x to both sides of the equation.
y=-3/5x-15/5 --> Divide -5 on both sides of the equation.
y=-3/5x-3 Reduce -15/5 into -3.

Since the equation is in the form y=mx+b, where m is the slope and b is the y-intercept, the y-intercept of the equation is -3.

Hope it helps!

Answer 4

Put the equation in the slope-intecept form: y = mx + b, where m is the slope and b is the y-intercept

-3x - 5y = 15
-5y = 15 + 3x
y = (15 + 3x)/-5
y = -3 - (3/5)x
y = -(3/5)x - 3

So, the y-intercept is -3

Answer 5

To find y-intercept, let x=0
-3x-5y=15
-3(0)-5y=15
-5y=15
y=-3

Answer 6

y = mx +b

-3x - 5y = 15
-5y = 3x +15
y = (-3/5)x - 3

y intercept is -3

Answer 7

Solve the equation for y so you can get it into the slope-intercept form: y = mx + b
m is the slope
b is the y intercept (the place where the line crosses the y axis)

When you slove for y you should get: y= -3/5 x - 3
so the y intercept should be -3.

Answer 8

y intercept is when x=0
so -3(0)-5y=15
0-5y=15
y = -3

Answer 9

Set x = 0
Then -5y = 15
y = -3
The y-intercept is (0,-3)

Answer 10

- 5y = 15
y = - 3 is y intercept.