Solving Equations Involving Rational Expressions
To solve an equation with rational expressions, we do not convert
the rational expressions to ones with a common denominator. Instead, we
multiply each side by the LCD to eliminate the denominators.
Example 1
An equation with two solutions
Solve
Solution
|
= x(x + 20)10 |
Multiply each side by
x(x + 20). |
|
= x(x + 20)10 |
Distributive property |
(x + 20)200 + x(300) |
= (x2 + 20x)10 |
Simplify. |
200x + 4000 + 300x |
= 10x2 + 200x |
|
4000 + 300x |
= 10x2 |
Combine like terms. |
400 + 30x |
= x2 |
Divide each side by 10. |
0 |
= x2 - 30x - 400 |
|
0 |
= (x - 40)(x + 10) |
Factor. |
x - 40 = 0 |
or |
x + 10 |
= 0 |
Set each factor equal
to 0. |
x = 40 |
or |
x |
= -10 |
|
Check these values in the original equation. The solution set is {-10, 40}.
|