Given: [tex]$f(x)=\frac{a}{x+b}+c$[/tex] and [tex]$g(x)=2x+5$[/tex]

The graph of [tex]$f$[/tex] has a vertical asymptote at [tex]$x=-1$[/tex]. Both graphs intersect the [tex]$y$[/tex]-axis, and the graph of [tex]$g$[/tex] intersects the horizontal asymptote of [tex]$f$[/tex] at the point [tex]$(-1, y)$[/tex].

Determine [tex]$a$[/tex], [tex]$b$[/tex], and [tex]$c$[/tex].



Answer :

To solve for the constants [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] in the given functions [tex]\(f(x)\)[/tex] and [tex]\(g(x)\)[/tex], we will use the provided information and conditions step by step.

### Step-by-Step Solution:

#### Step 1: Finding [tex]\(b\)[/tex]
We know that the graph of [tex]\(f(x) = \frac{a}{x+b} + c\)[/tex] has a vertical asymptote at [tex]\(x = -1\)[/tex]. A vertical asymptote occurs where the denominator of the fraction is zero. Therefore, we set the denominator to zero and solve for [tex]\(b\)[/tex]:

[tex]\[ x + b = 0 \quad \text{at} \quad x = -1 \][/tex]

[tex]\[ -1 + b = 0 \][/tex]

[tex]\[ b = -1 \][/tex]

Thus, [tex]\(b = -1\)[/tex].

#### Step 2: Finding the y-intercepts
Both functions [tex]\(f(x)\)[/tex] and [tex]\(g(x)\)[/tex] intersect the [tex]\(y\)[/tex]-axis. The [tex]\(y\)[/tex]-axis intersection occurs when [tex]\(x = 0\)[/tex].

For [tex]\(f(x)\)[/tex], the intersection point is:

[tex]\[ f(0) = \frac{a}{0 + b} + c = \frac{a}{-1} + c = -a + c \][/tex]

For [tex]\(g(x)\)[/tex], the intersection point is:

[tex]\[ g(0) = 2 \cdot 0 + 5 = 5 \][/tex]

Since both functions intersect the [tex]\(y\)[/tex]-axis at the same point, we have:

[tex]\[ -a + c = 5 \][/tex]

#### Step 3: Finding the horizontal asymptote [tex]\(c\)[/tex]
We are given that function [tex]\(g\)[/tex] intersects the horizontal asymptote of function [tex]\(f\)[/tex] at the point [tex]\((-1, y)\)[/tex]. The horizontal asymptote of [tex]\(f\)[/tex] is given by the constant term [tex]\(c\)[/tex] as [tex]\(x\)[/tex] approaches infinity.

First, we calculate the value of [tex]\(g(x)\)[/tex] at [tex]\(x = -1\)[/tex]:

[tex]\[ g(-1) = 2 \cdot (-1) + 5 = -2 + 5 = 3 \][/tex]

Since [tex]\(g(x)\)[/tex] intersects the horizontal asymptote of [tex]\(f(x)\)[/tex] at this point, it means:

[tex]\[ c = 3 \][/tex]

#### Step 4: Finding [tex]\(a\)[/tex]
Using the equation from step 2, where [tex]\(-a + c = 5\)[/tex], and substituting [tex]\(c = 3\)[/tex]:

[tex]\[ -a + 3 = 5 \][/tex]

Solving for [tex]\(a\)[/tex]:

[tex]\[ -a = 5 - 3 \][/tex]

[tex]\[ -a = 2 \][/tex]

[tex]\[ a = -2 \][/tex]

### Summary:
We have determined the constants as follows:

[tex]\[ a = -2 \][/tex]
[tex]\[ b = -1 \][/tex]
[tex]\[ c = 3 \][/tex]

Thus, the values of [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] are [tex]\(-2\)[/tex], [tex]\(-1\)[/tex], and [tex]\(3\)[/tex] respectively.