Question

Find all solutions to the following system of equations -y²+6y+x-9=0 ; 6y=x+27.Illustrate with a graph.

Answer 1

Answer:

The solution to the system is the pair (9, 6)

Step-by-step explanation:

Hi!

First, let´s write the system of equations:

-y² + 6y + x -9 = 0

6y = x +27

The solutions of the system are the pairs (x, y) that satisfy both equations.

Let´s take the second equation and solve it for x:

6y = x +27

Subtract 27 from both sides of the equation

6y - 27 = x

Now, we can replace x in the first equation and solve it for y:

-y² + 6y + x -9 = 0

-y² + 6y + 6y - 27 -9 = 0

-y² + 12y - 36 = 0

Notice that -y² + 12y - 36 = -(y - 6)², then:

-(y - 6)² = 0

y - 6 = 0

y = 6

(alternatively you can solve the quadratic equation using the quadratic formula).

Now let´s find the value of x:

x = 6y -27

x = 6·6 -27

x = 9

The solution to the system is the pair (9, 6)

Please see the attached figure. The point where the curves intersect is the solution to the system.