Which represents the solution(s) of the system of equations [tex]y=-x^2+6x+16[/tex] and [tex]y=-4x+37[/tex]?

Determine the solution set algebraically.

A. [tex](3, 25)[/tex]

B. [tex](-3, 49)[/tex]

C. [tex](3, 25)[/tex] and [tex](7, 9)[/tex]

D. [tex](-3, 49)[/tex] and [tex](-7, 65)[/tex]



Answer :

To find the solution(s) of the system of equations algebraically, we need to solve for the values of [tex]\(x\)[/tex] and [tex]\(y\)[/tex] that satisfy both equations simultaneously:

1. [tex]\( y = -x^2 + 6x + 16 \)[/tex]
2. [tex]\( y = -4x + 37 \)[/tex]

Since both equations equal [tex]\(y\)[/tex], we can set them equal to each other to solve for [tex]\(x\)[/tex]:

[tex]\[ -x^2 + 6x + 16 = -4x + 37 \][/tex]

Rearrange the equation so that all terms are on one side, resulting in a standard quadratic equation:

[tex]\[ -x^2 + 6x + 16 + 4x - 37 = 0 \][/tex]

Combine like terms:

[tex]\[ -x^2 + 10x - 21 = 0 \][/tex]

Multiply the entire equation by [tex]\(-1\)[/tex] to make the coefficient of [tex]\(x^2\)[/tex] positive:

[tex]\[ x^2 - 10x + 21 = 0 \][/tex]

To solve this quadratic equation, we can use the quadratic formula, [tex]\( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)[/tex], where [tex]\(a = 1\)[/tex], [tex]\(b = -10\)[/tex], and [tex]\(c = 21\)[/tex].

First, calculate the discriminant:

[tex]\[ b^2 - 4ac = (-10)^2 - 4(1)(21) = 100 - 84 = 16 \][/tex]

Since the discriminant is positive, there are two real solutions. Calculate the solutions using the quadratic formula:

[tex]\[ x = \frac{-(-10) \pm \sqrt{16}}{2(1)} = \frac{10 \pm 4}{2} \][/tex]

This gives us two values for [tex]\(x\)[/tex]:

[tex]\[ x = \frac{10 + 4}{2} = \frac{14}{2} = 7 \][/tex]

[tex]\[ x = \frac{10 - 4}{2} = \frac{6}{2} = 3 \][/tex]

Now, we need to find the corresponding [tex]\(y\)[/tex] values for these [tex]\(x\)[/tex] values using either of the original equations. Let's use [tex]\( y = -4x + 37 \)[/tex]:

For [tex]\( x = 7 \)[/tex]:

[tex]\[ y = -4(7) + 37 = -28 + 37 = 9 \][/tex]

So, one solution is [tex]\( (7, 9) \)[/tex].

For [tex]\( x = 3 \)[/tex]:

[tex]\[ y = -4(3) + 37 = -12 + 37 = 25 \][/tex]

So, another solution is [tex]\( (3, 25) \)[/tex].

Thus, the solution set to the system of equations [tex]\( y = -x^2 + 6x + 16 \)[/tex] and [tex]\( y = -4x + 37 \)[/tex] is:

[tex]\[ (3, 25) \text{ and } (7, 9) \][/tex]

Therefore, the correct answer is:
[tex]\[ (3, 25) \text{ and } (7, 9) \][/tex]