The y-intercept is the point where the graph intersects the y-axis. To graph, any role that is that the form y=f(x) recognize the intercepts is really important. There space two species of intercepts that a function can have. They are the x-intercept and the y-intercept. An intercept that a duty is a allude where the graph that the function cuts the axis. Let us understandthe an interpretation of y-intercept and also the calculation of y-intercept utilizing the y-intercept formula through a couple of examples.

You are watching: What is the y-intercept of the function f(x) = –x + ?

1.What is Y-Intercept?
2.Y-Intercept of a right Line
3.Y-Intercept Formula
4.How To discover The Y-Intercept?
5. FAQs top top Y-Intercept

What is Y-Intercept?

The y-intercept the a graph is (are) the point(s) where the graph intersects the y-axis. We know that the x-coordinate the any point on the y-axis is 0. Therefore the x-coordinate the a y-intercept is 0.


Here is an example of a y-intercept. Take into consideration the line y = x+ 3. This graph meets the y-axis in ~ the suggest (0,3). Therefore (0,3) is the y-intercept that the heat y = x+ 3.


Y-Intercept the a right Line

When two planes intersect we get a directly line. A directly line have the right to be horizontal or vertical or slanting. The y intercept of a horizontal heat is (0, a) and also the y intercept the a upright linedoes no exist. Let us find out to uncover the y intercept that a straight line represented in different forms.

Y-Intercept in The general Form

The equation that a right line in general form is ax+by+c=0. Because that y-intercept, us substitute x=0 and solve it for y.

a(0)+ by + c =0

by + c =0

y = - c/b

Thus, the y-intercept of the equation the a line in general type is:(0, -c/b) or -c/b

y-Intercept in The Slope-Intercept Form

The equation the the line in the slope-intercept kind is, y=mx+b. By the definition of the slope-intercept type itself, b is the y-intercept of the line. You shot by substituting x=0 in y=mx+b and also see whether you get b together the y-intercept. Thus, the y-intercept of the equation that a heat in the slope-intercept kind is (0, b) or b.

y-Intercept in The Point-Slope Form

The equation of the heat in the point-slope form is, y-y(_1)=m x-x(_1). Because that y-intercept, us substitute x=0 and also solve it for y.

y-y(_1) = m (0-x(_1) )

y-y(_1)= - mx(_1)

y = y(_1) - mx(_1)

Thus, the y-intercept that the equation the a heat in the point-slope type is: (0, y(_1) - mx(_1)) or y(_1) - mx(_1)

Y-Intercept Formula

The y-intercept of a role is a point where the graph would meet the y-axis. The x-coordinate the any suggest on the y-axis is 0 and also we usage this truth to derive the formula to discover the y-intercept. I.e., the y-intercept the a role is the the kind (0, y). Thus, the formula to find the y-intercept is:


Y Intercept Formula

To uncover the y-intercept the a duty y = f(x),

we simply substitute x = 0 in it.solve because that y.represent the y-intercept as the allude (0, y).

How To uncover Y-Intercept?

We have derived the formulas to uncover the y-intercept of a line wherein the equation that the straight line is in different forms. In fact, we execute not have to apply any type of of this formulas to discover the y-intercept that a straight line. The y-intercept of the polynomial function of the kind (y=a_1x^n+a_2 x^n-1+...+a_n) is simply its constant term (a_n) (or) ((0, a_n)).

We just substitute x=0 in the equation of the line and also solve because that y. Then the corresponding y intercept is y or (0, y).

Equation that Line

Substitute x=0 and solve for y

y intercept

3x+5y -6=0

3(0)+5y-6 =0


y =6/5

6/5 (or) ( 0, 6/5)

y= 2x-3

y=2(0)-3=-3-3 (or) (0, -3)

The y-intercept that a role can be easily found by graphing it using the graphing calculator and also locating the allude where the graph cut the y-axis. A function has just one y-intercept due to the fact that otherwise, it stops working the vertical line test. The y- intercept that the 2nd equation that the table is presented in the graph below.


y-intercept of a Quadratic duty or a Parabola

The procedure because that finding the y-intercept of a quadratic role (parabola) is the same as the of a line (as discussed in the ahead section). If a quadratic equation is given, substitute x = 0 and solve for y to obtain the y intercept.


Equation the Parabola

Substitutex=0andsolve for y


y= x2 -2x -3

y=02-2(0)-3=-3-3 (or) (0, -3)

y= 2x2+5x-3

y=2(0)2+5(0)-3=-3-3 (or) (0, -3)


Important Notes

We substitute x=0 and also solve for y to find the y-intercept.In the same way, we substitute y=0 and solve for x to find the x-intercept.The present parallel to the y-axis cannot have y-intercepts together they perform not intersect the y-axis anywhere.The y-intercept of a line is widely used as one initial point while graphing a heat by plotting two points.

also Check:

Example 1: Find the y-intercept the the following features using the formula to discover the y-intercept: a) y = x2 - 3x + 2 b) y = (x2 - 1) / x


Using the y-intercept formula, to find the y-intercept that a function, we just substitute x = 0 in it and also solve for y.

a) substitute x = 0 in y = x2 - 3x + 2, we get

y = 02 - 3(0) + 2 = 2

So the y-intercept = (0, y) = (0, 2)

b) instead of x = 0 in y = (x2 - 1) / x, us get

y = (02 - 1) / 0 = -1/0 = not defined

So the given function doesn't have actually a y-intercept.

Answer: a) (0, 2); b) Does not Exist

Example 2: If the y-intercept of a role y = a (x - 1) (x - 2) (x - 3) is (0, 12), then uncover the value of "a".


The equation of the given duty is:

y = a (x - 1) (x - 2) (x - 3)

Using the y-intercept formula, it have the right to be derived by substituting x = 0 in it.

See more: Yes, Solid Toothpaste Is Toothpaste A Solid Or Liquid ?: Askscience

y = a (0 - 1) (0 - 2) (0 - 3) = -6a

So the y-intercept is (0, -6a)

But the difficulty says the the y-intercept that the given duty is (0, 12). Thus,

-6a = 12

Dividing both sides by -6,

a = -2

Answer: a = -2

Example 3: If the y-intercept that the duty y = 3x2 + ax + b is (0, -5) then discover the worth of 'b'.


By using the y intercept formula the y-intercept that the given duty is obtained by substituting x = 0