Expressions containing fractions and simplifying

I have an expression;

(1 - u)(2u + 1/3) I am asked to multiply out the brackets and simplify. I am concerned about the fraction because I cannot find any examples in my course book to help with this type of expression.

am I doing it correctly by this method;

(1 - u)(2u + 1/3) = 2u + 3 - 2u^2 - 3u

Thanks

David

Re: Expressions containing fractions and simplifying

Nearly.

$\displaystyle 4\times{\frac{1}{3}}=\frac{4}{3}$

Just multiply the value by the numerator of the fraction.

So what would:

$\displaystyle -u\times\frac{1}{3}$ be?

Just FOIL it out as you normally would. (Wink)

Re: Expressions containing fractions and simplifying

Quote:

Originally Posted by

**Quacky** Nearly.

$\displaystyle 4\times{\frac{1}{3}}=\frac{4}{3}$

Just multiply the value by the numerator of the fraction.

So what would:

$\displaystyle -u\times\frac{1}{3}$ be?

Just FOIL it out as you normally would. (Wink)

- u Yes

Re: Expressions containing fractions and simplifying

I'm confused by your response. Do you understand where you were going wrong?

Re: Expressions containing fractions and simplifying

Quote:

Originally Posted by

**Quacky** I'm confused by your response. Do you understand where you were going wrong?

I will have to look up FOIL to remember it, but please advise if I misunderstood.

- u x 1/3 = - u / 3

No?

Re: Expressions containing fractions and simplifying

That's right. FOIL is a general approach to quadratics; multiply the:

First,

Outside,

Inside

Last

...terms together. You don't have to use it to expand if you prefer not to. The method you used in the original post is fine except for a very minor error when taking the fraction into account.

Re: Expressions containing fractions and simplifying

Quote:

Originally Posted by

**Quacky** That's right. FOIL is a general approach to quadratics; multiply the:

First,

Outside,

Inside

Last

...terms together. You don't have to use it to expand if you prefer not to. The method you used in the original post is fine except for a very minor error when taking the fraction into account.

So I made TWO mistakes then?

Expression;

(1 - u)(2u + 1/3) = 2u + 1 - 2u^2 - u/3

Thank you

David

Re: Expressions containing fractions and simplifying

Quote:

Originally Posted by

**David Green** So I made TWO mistakes then?

Expression;

(1 - u)(2u + 1/3) = 2u +** 1 **- 2u^2 - u/3

Thank you

David

The value marked in red is unfortunately wrong because $\displaystyle 1 \cdot \frac13 = \frac13$.