212k views
0 votes
Solve the equation (x-4) (x+9) = 0


User Atanu
by
8.0k points

1 Answer

5 votes

Answer:

x = 4,-9

Explanation:

This is a quadratic equation in x-intercept pattern. Since this is completely factored, we can simply solve the equation like a linear.

First, separate two equations. Let r be the roots of equation, therefore:


\displaystyle \large{r=\begin{cases}x-4=0\\ x+9=0 \end{cases}}

I use the r-variable to denote the roots of equations (not necessary), simply separate both then solve it like a linear.


\displaystyle \large{r=\begin{cases}x-4+4=0+4\\ x+9-9=0-9 \end{cases}}\\\displaystyle \large{r=\begin{cases}x=4\\ x=-9 \end{cases}}

Therefore, the roots of equation are x = 4 or x = -9. In short, we can write as x = 4,-9.

The reason why we use OR instead of AND because one of x-values satisfy the quadratic equation hence ‘or’ is more suitable than ‘and’. However, you must write all valid solutions instead of writing only one x-value from two.

___________________

Let me know in the comment if you have any questions.

User Supercat
by
7.2k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.