The domain of a variable Here comes Trouble! The domain of a variable

Baby’s Room At home, the baby’s domain is his bedroom and the family room and…everywhere you see toys! When baby comes to visit my house, however, things are different. I don’t have any babies at home so my house isn’t child-proofed.

Baby in the Living Room I can tell the Mom he’ll be just fine in the living room. But within the first 5 minutes I’m saying: Oh, no! Not the fireplace! Come away from there. Oops – that crystal vase is going to fall! Omigosh – the stairs!

Baby’s Domain At my house, baby’s domain is severely restricted. He can go anywhere in the living room except… And that’s what happens to lots of variables. We say that a variable is a letter that stands for a number, but…

Domain of a Variable What are some of the numbers that a letter can’t stand for? It all depends on the expression the variable is in – just like with the baby – it depends on whose house he’s visiting. Let’s say we have the expression

Domain of a Variable What is the First Commandment of Mathematics? x can’t be what number?

The First Commandment of Mathematics Thou shalt not divide by zero! x can’t be what number? x can be any number except zero. The domain of x is all real numbers except zero.

Domain of a Variable Think about the First Commandment of Mathematics. Can x = 0? Sure – there’s nothing wrong with

The First Commandment of Mathematics Thou shalt not divide by zero! x can’t be what number? Let’s find out. x can be any number but 5 because 5 would make the denominator 0. The domain of x is all real numbers except 5.

Domain of a Variable Think about the First Commandment of Mathematics. Can x = 0? Sure – there’s nothing wrong with

The First Commandment of Mathematics Thou shalt not divide by zero! x can’t be what number? Let’s find out. x can be any number except -6 because -6 would make the denominator =0. The domain of x is all real numbers except -6.

When you’re finding the domain, be on the lookout for pitfalls! Finding the domain of a variable is like having a baby come to visit. His domain is everywhere except the places that make you say Omigosh – stop him! When you’re finding the domain, be on the lookout for pitfalls! So far, the only pitfall we know about is division by zero. Set the denominator equal to zero and see what value would make it zero. The domain will be all real numbers except for that number.