Domain of Rational Numbers Lesson

Domain of Rational Numbers

What is Domain and How Do You Find the Domain of a Rational Number?

Let MathWithDabit guide your through it.

Poll

I know how to find DOMAIN OF A RATIONAL NUMBER and am ready for my quiz.

Domain Vs. Exclusions

• The values that can NOT be put in the unknown variables.

• Use these numbers and you'll get an undefined amount.​

​Exclusions

• All the values that CAN be put in for the unknown variables.

• Usually this will be all real numbers except a few values.​

Domain

Watch this video and see how you find your domain (numbers you want) and the exclusions (numbers you don't want).

​

​Domain will be:

​All the numbers in the set that will work!

Multiple Choice

Definition of Domain

• Values where denominator equals zero

• Variables (undefined values)

• All the input values that will define the expression

• Real numbers

Multiple Choice

Definition of Exclusions

• The values of x that will make the expression undefined.

• The values of x that work.

• Defined values of y.

• The values of x that will make the expression defined.

Open Ended

How do you find the excluded values for the domain?

Multiple Choice

The Uber van you just called for only holds TEN people. Yes, 10 people will fit in the van. When writing formulas to obtain costs, what would be a reasonable DOMAIN?

• $$x<10$$

• $$x\le10$$

• $$x>10$$

• $$x\ge10$$

Multiple Choice

How do you write the DOMAIN of an expresion?

• x $$\ne$$  3, 9

• Is all real numbers except when x = 3 and 9

• x = 3, 9

• All real numbers

Multiple Choice

What is the domain of   $$f\left(x\right)=\frac{2}{x+3}$$  

• all real numbers except -3

• all real numbers except 3

• all real numbers except -2

• all real numbers except 2

Multiple Choice

$$What\ is\ the\ domain\ of\ f\left(x\right)=\ \frac{2\ +\ x}{2x}$$  

• all real numbers except 1/2

• x = 0

• all real numbers except -2

• all real numbers except 0

Multiple Choice

Find the domain of the function:

$$f\left(x\right)=\frac{2x^2+4x-6}{x^2-5x+6}$$  

• $$all\ Real\ numbers\ x\ne2,3$$  

• $$all\ Real\ numbers\ x\ne-3,-2$$  

• $$all\ Real\ numbers\ x\ne-3,1$$  

• $$all\ Real\ numbers\ x\ne-1,3$$  

Multiple Choice

Find the domain.

$$\frac{8x-3}{\left(x+5\right)\left(x-2\right)}$$  

• All real numbers except 5 and 2

• x = -5, 2

• All real numbers except -5 and -2

• All real numbers except -5 and 2

Poll

How confident are you in FINDING DOMAIN OF RATIONAL NUMBERS?