# Evaluating a variable expression 2

#### rodgerst414

##### New member
Evaluate the variable expression when a=3,b=1 and c=-2

b^2-4ac. This is new to me so please explain how to do this.

#### MarkFL

Staff member
Okay, what you want to do is let the 3 variables take on the given values, and put these into the expression you are asked to evaluate:

This would give us:

$(1)^2-4(3)(-2)$

Now, can you compute this expression following the rules of arithmetic?

#### MarkFL

Staff member
For future topics, I highly recommend using a title that briefly describes the problem. For example, a good title for this topic is "Evaluating a variable expression". This lets our helpers know exactly what kind of problem is being discussed.

#### rodgerst414

##### New member
For future topics, I highly recommend using a title that briefly describes the problem. For example, a good title for this topic is "Evaluating a variable expression". This lets our helpers know exactly what kind of problem is being discussed.

#### MarkFL

Staff member
Follow the same procedure you used to create this topic. You are welcome to create as many topics as there are problems with which you need help.

We do request that as you learn from the help given in previous problems that you apply this to subsequent problems, and show what you think you should do. This allows us to see how you are progressing, and what things may need to be made more clear.

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