Solve for x in the following equation.
Example 4 :
Rewrite the equation in an equivalent form without denominators by multiplying both sides by 6.
Since the equation is not easily factored, we will skip this method.
Method 2:Completing the square
Add 5 to both sides of the equation
Divide both sides by 4 :
Add both sides of the equation:
Factor the left side and simplify the right side :
Take the square root of both sides of the equation :
Add to both sides of the equation.
Method 3:Quadratic Formula
The quadratic formula is
In the equation , a is the coefficient of the term, b is the coefficient of the x term, and c is the constant. Substitute 4 for a, -90 for b , and -5 for c in the quadratic formula and simplify.
Graph and y=0. The graph of y=0 is nothing more than the x-axis. So what you will be looking for is where the graph of crosses the x-axis. Another way of saying this is that the x-intercepts are the solutions to this equation.
You can see from the graph that there are two x-intercepts located at 22.5554190546 and -0.055419054595. This means that there are two real answers: x=22.5554190546 and
The answers are 22.5554190546 and -0.055419054595. These answers may or may not be solutions to the original equation. You must check the answers with the original equation.
Check these answers in the original equation.
Check the solution x=22.5554190546 by substituting 22.5554190546 in the original equation for x. If the left side of the equation equals the right side of the equation after the substitution, you have found the correct answer.
Check the solution x=-0.055419054595 by substituting -0.055419054595 in the original equation for x. If the left side of the equation equals the right side of the equation after the substitution, you have found the correct answer.
The solutions to the equation are 22.5554190546 and - 0.055419054595.
Comment:You can use the exact solutions to factor the original equation.
For example, since , then
Since , then
Since the product
Then and are factors of .
But not the only factors.
If we multiply both sides by , we will get :
Therefore is factored as
This means that and are factors of
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