Find all values of $x$ such that $\dfrac{x}{x+4} = -\dfrac{9}{x+3}$. If you find more than one value, then list your solutions in increasing order, separated by commas.

Respuesta :

We start with

[tex]\dfrac{x}{x+4} = -\dfrac{9}{x+3}[/tex]

Assuming that [tex]x \notin \{-4,\ -3\}[/tex] we can cross multiply the equation:

[tex]x(x+3) = -9(x+4) \iff x^2+3x=-9x-36 \iff x^2+12x+36=0[/tex]

You can recognize the perfect square pattern in the quadratic equation:

[tex]x^2+12x+36 = (x)^2 + 2\cdot x \cdot 6 + (6)^2 = (x+6)^2[/tex]

So, we have

[tex]x^2+12x+36=0 \iff (x+6)^2 = 0 \iff x+6=0 \iff x=-6[/tex]

Which is the only solution, with multiplicity 2.

The value of x is -6 and this can be determined by simplifying the given expression by using the arithmetic operations.

Given :

Expression  --    [tex]\dfrac{x}{x+4}=-\dfrac{9}{x+3}[/tex]

The following steps can be used in order to determine the values of 'x':

Step 1 - The arithmetic operations can be used in order to determine the values of 'x'.

Step 2 - Write the given expression.

[tex]\dfrac{x}{x+4}=-\dfrac{9}{x+3}[/tex]

Step 3 - Cross multiply in the above expression.

[tex]x(x+3)=-9(x+4)[/tex]

Step 4 - Further simplify the above expression.

[tex]x^2+3x+9x+36=0[/tex]

[tex]x^2+12x+36=0[/tex]

Step 5 - Factorize the above quadratic equation.

[tex]x^2+6x+6x+36=0[/tex]

x(x + 6) + 6(x + 6) = 0

[tex](x+6)^2=0[/tex]

So, the value of 'x' is -6.

For more information, refer to the link given below:

https://brainly.com/question/17177510