# Multiplying Rational Expressions

#### crappiefisher26

##### New member
How did they get this?

. . .(2x^3 / 5y^2) * (10y / 3x^2)

. . .= (2x^3 * 10y) / (5y^2 * 3x^2)

. . .= 4x / 3y

#### Denis

##### Senior Member
crappiefisher26 said:
how did they get this.
(2x^3/5y^2)*(10y/3x^2)=(2x^3*10y)/5y^2*3x^2)=4x/3y
"they got this" by simple multiplication, then simplification :!:

EXAMPLE of simplification: x^5 / x^3 = x^(5-3) = x^2

#### crappiefisher26

##### New member
Multiplying ration Expressions

Thanks Dennis. Heres the questions im stuck on

3a/2*4/a^2

how did they get 4x/3y from (2x^3*10y)/(5y^2*3x^2)

im not quite sure i understand that yet.

#### stapel

##### Super Moderator
Staff member
Re: Multiplying ration Expressions

crappiefisher26 said:
how did they get 4x/3y from (2x^3*10y)/(5y^2*3x^2)
"They" did just what the tutor said: They multiplied the fractions and then simplified.

Are you not familiar with multiplying fractions? Because you can't very well work with rational expressions unless you're very solid on regular (numerical) fractions. If you don't understand how "they" go from, say, (3/5)(20/21) to (1/1)(4/7) = 4/7, then you need to back up a bit before trying to work with rational expressions.

Eliz.