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Use substitution or elimination to find the solutions to the system.
y = x² +7x+8
y=x+3​

1 Answer

4 votes

Answer:


\sf (-5, -2) and
\sf (-1, 2)

Explanation:

Let's use substitution to find the solutions to the system. The system is:

1.
\sf y = x^2 + 7x + 8

2.
\sf y = x + 3

Since both expressions are equal to
\sf y, we can set them equal to each other:


\sf x^2 + 7x + 8 = x + 3

Now, let's rearrange the equation and set it to zero:


\sf x^2 + 6x + 5 = 0

Now, doing middle term factorization to the quadratic:


\sf x^2 + (5+1)x + 5 = 0


\sf x^2 + 5x + 1x + 5 = 0


\sf x(x+5)+1(x+5) = 0


\sf (x + 5)(x + 1) = 0

This gives two possible solutions:

1.
\sf x + 5 = 0
\sf \Rightarrow
\sf x = -5

2.
\sf x + 1 = 0
\sf \Rightarrow
\sf x = -1

Now that we have the values of
\sf x, we can substitute them back into either of the original equations to find the corresponding
\sf y values.

Let's use the second equation for this:

For
\sf x = -5:


\sf y = (-5) + 3 = -2

For
\sf x = -1:


\sf y = (-1) + 3 = 2

Therefore, the solutions to the system are
\sf (-5, -2) and
\sf (-1, 2).

User Costa Zachariou
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