Given [tex]f(x) = x^2 - 3x - 4[/tex] and [tex]g(x) = |x + 3| - 2[/tex], which value is a solution to the equation [tex]f(x) = g(x)[/tex]?

A. -4
B. -3
C. -1
D. 4



Answer :

To solve for the values of [tex]\( x \)[/tex] where [tex]\( f(x) = g(x) \)[/tex], we need to solve the equation

[tex]\[ x^2 - 3x - 4 = |x + 3| - 2. \][/tex]

First, let's understand the function [tex]\( g(x) = |x + 3| - 2 \)[/tex]. The absolute value function [tex]\( |x + 3| \)[/tex] has two cases depending on the value of [tex]\( x \)[/tex]:

1. If [tex]\( x + 3 \geq 0 \)[/tex] (i.e., [tex]\( x \geq -3 \)[/tex]), then [tex]\( |x + 3| = x + 3 \)[/tex].
2. If [tex]\( x + 3 < 0 \)[/tex] (i.e., [tex]\( x < -3 \)[/tex]), then [tex]\( |x + 3| = -(x + 3) = -x - 3 \)[/tex].

Let's look at each case separately:

### Case 1: [tex]\( x \geq -3 \)[/tex]

Here, [tex]\( |x + 3| = x + 3 \)[/tex]. Substituting this into [tex]\( g(x) \)[/tex], we get:

[tex]\[ g(x) = (x + 3) - 2 = x + 1. \][/tex]

So, we need to solve the equation:

[tex]\[ x^2 - 3x - 4 = x + 1. \][/tex]

Rearrange to form a quadratic equation:

[tex]\[ x^2 - 3x - 4 - x - 1 = 0 \][/tex]
[tex]\[ x^2 - 4x - 5 = 0. \][/tex]

Next, solve this quadratic equation by factoring:

[tex]\[ x^2 - 4x - 5 = (x - 5)(x + 1) = 0. \][/tex]

Thus, the solutions are:

[tex]\[ x = 5 \quad \text{or} \quad x = -1. \][/tex]

We need to check if these solutions lie within the range [tex]\( x \geq -3 \)[/tex]:

- [tex]\( x = 5 \)[/tex] is valid.
- [tex]\( x = -1 \)[/tex] is valid.

### Case 2: [tex]\( x < -3 \)[/tex]

Here, [tex]\( |x + 3| = -x - 3 \)[/tex]. Substituting this into [tex]\( g(x) \)[/tex], we get:

[tex]\[ g(x) = (-x - 3) - 2 = -x - 5. \][/tex]

So, we need to solve the equation:

[tex]\[ x^2 - 3x - 4 = -x - 5. \][/tex]

Rearrange to form a quadratic equation:

[tex]\[ x^2 - 3x - 4 + x + 5 = 0 \][/tex]
[tex]\[ x^2 - 2x + 1 = 0. \][/tex]

Next, solve this quadratic equation by factoring:

[tex]\[ x^2 - 2x + 1 = (x - 1)^2 = 0. \][/tex]

Thus, the solution is:

[tex]\[ x = 1. \][/tex]

We need to check if this solution lies within the range [tex]\( x < -3 \)[/tex]:

- [tex]\( x = 1 \)[/tex] is not valid in this case.

Hence, the only valid solutions are [tex]\( x = 5 \)[/tex] and [tex]\( x = -1 \)[/tex].

From the given options:
A. -4
B. -3
C. -1
D. 4

The valid solution present in the options is:
[tex]\[ \boxed{-1} \][/tex]