Multiply and divide rational expressions
Key Notes :
To divide by a fraction, multiply by its reciprocal.
Learn with an example
Multiply. Write your answer in simplest form.
7g/6 . (4g2 -11g-3) = _________
Multiply
7g/6 . (4g2 -11g-3)
7g/6 . 4g2 -11g-3/1 Rewrite the second expression as a fraction
7g(4g2 -11g-3) /6 Multiply the numerators and multiply the denominators
7g(4g+1)(g-3)/6 Factorise the quadratic
The answer is 7g(4g+1)(g-3)/6 , which can also be written as
28g3 -77g2 -21g /6.
Divide. Write your answer in simplest form.
c-4/2c ÷ (2c+5) = _________
Divide.
c-4/2c ÷ (2c+5)
c-4/2c ÷ 2c+5/1 Rewrite the second expression as a fraction
c-4/2c ÷ 1/ 2c+5 To divide, multiply by the reciprocal
c-4/2c(2c+5) Multiply the numerators and multiply the denominators
The answer is c-4/2c(2c+5) , which can also be written as
c-4/4c2 +10c
Multiply. Write your answer in simplest form.
v+5/3v2 -4v . (4v+5) = _____________
Multiply
v+5/3v2 -4v . (4v+5)
v+5/3v2 -4v . (4v+5)/1 Rewrite the second expression as a fraction
v+5/v(3v-4) . (4v+5)/1 Factorise out the GCF
(v+5)(4v+5)/v(3v-4) Multiply the numerators and multiply the denominators
The answer is (v+5)(4v+5)/v(3v-4) , which can also be written as
4v2 +25v+25/3v2 -4v .
let’s practice!
