What is the result of substituting [tex]y[/tex] in the bottom equation?

[tex]\[
\begin{array}{l}
y = x + 3 \\
y = x^2 + 2x - 4
\end{array}
\][/tex]

A. [tex]y = (x + 3)^2 + 2(x + 3) - 4[/tex]
B. [tex]x + 3 = x^2[/tex]
C. [tex]y = x^2 + 2x - 4 - (x + 3)[/tex]
D. [tex]x + 3 = x^2 + 2x - 4[/tex]



Answer :

To determine the correct result of substituting for [tex]\( y \)[/tex] in the bottom equation, let's start by analyzing the two given equations:

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

We need to substitute [tex]\( y \)[/tex] from the first equation into the second equation. The substitution process works as follows:

1. From the first equation, we know that [tex]\( y = x + 3 \)[/tex].

2. Substitute [tex]\( y = x + 3 \)[/tex] into the second equation:

[tex]\[ y = x^2 + 2x - 4 \][/tex]

This becomes:

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

Let's check the options given:

- Option A: [tex]\( y = (x + 3)^2 + 2(x + 3) - 4 \)[/tex]

This option introduces an incorrect manipulation and unnecessary squaring. It is not the result of simple substitution.

- Option B: [tex]\( x + 3 = x^2 \)[/tex]

This option simplifies the original substitution and omits critical terms, thus it is incorrect.

- Option C: [tex]\( y = x^2 + 2x - 4 - (x + 3) \)[/tex]

This option does not properly substitute for [tex]\( y \)[/tex]. Instead, it introduces a subtraction that isn’t present in the original substitution.

- Option D: [tex]\( x + 3 = x^2 + 2x - 4 \)[/tex]

This correctly shows the result of substituting [tex]\( y \)[/tex] from the first equation into the second equation.

The correct answer is thus:

D. [tex]\( x + 3 = x^2 + 2x - 4 \)[/tex]