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{:[x=2y+5],[y=(2x-3)(x+9)]:}
How many ordered pairs 
(x,y) satisfy the system of equations shown above?
A) 0
B) 1
C) 2
D) Infinitely many

x=2y+5y=(2x3)(x+9) \begin{array}{l} x=2 y+5 \\ y=(2 x-3)(x+9) \end{array} \newlineHow many ordered pairs (x,y) (x, y) satisfy the system of equations shown above?\newlineA) 00\newlineB) 11\newlineC) 22\newlineD) Infinitely many

Full solution

Q. x=2y+5y=(2x3)(x+9) \begin{array}{l} x=2 y+5 \\ y=(2 x-3)(x+9) \end{array} \newlineHow many ordered pairs (x,y) (x, y) satisfy the system of equations shown above?\newlineA) 00\newlineB) 11\newlineC) 22\newlineD) Infinitely many
  1. Understand the Equations: Understand the system of equations.\newlineWe have a system of two equations:\newline11) x=2y+5x = 2y + 5\newline22) y=(2x3)(x+9)y = (2x - 3)(x + 9)\newlineWe need to find the number of ordered pairs (x,y)(x, y) that satisfy both equations simultaneously.
  2. Substitute and Solve: Substitute the expression for xx from the first equation into the second equation.\newlineFrom equation 11, we have x=2y+5x = 2y + 5. We can substitute this into equation 22 in place of xx to solve for yy.\newliney=(2(2y+5)3)((2y+5)+9)y = (2(2y + 5) - 3)((2y + 5) + 9)
  3. Simplify the Expression: Simplify the equation obtained after substitution.\newliney=(4y+103)(2y+14)y = (4y + 10 - 3)(2y + 14)\newliney=(4y+7)(2y+14)y = (4y + 7)(2y + 14)\newlineNow, we will expand this to get a quadratic equation in terms of yy.
  4. Expand and Simplify: Expand the equation and simplify.\newliney=(4y+7)(2y+14)y = (4y + 7)(2y + 14)\newliney=8y2+28y+14y+98y = 8y^2 + 28y + 14y + 98\newliney=8y2+42y+98y = 8y^2 + 42y + 98
  5. Set Equation to Zero: Move all terms to one side to set the equation to zero.\newline0=8y2+42y+98y0 = 8y^2 + 42y + 98 - y\newline0=8y2+41y+980 = 8y^2 + 41y + 98
  6. Factor Quadratic Equation: Factor the quadratic equation, if possible.\newlineWe need to factor 8y2+41y+988y^2 + 41y + 98. However, this does not factor nicely, and we may need to use the quadratic formula to find the roots.
  7. Use Quadratic Formula: Use the quadratic formula to find the roots of the equation.\newlineThe quadratic formula is y=b±b24ac2ay = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}, where a=8a = 8, b=41b = 41, and c=98c = 98.\newlineDiscriminant = b24ac=4124(8)(98)b^2 - 4ac = 41^2 - 4(8)(98)\newlineDiscriminant = 168131361681 - 3136\newlineDiscriminant = 1455-1455
  8. Analyzing the Discriminant: Analyze the discriminant.\newlineSince the discriminant is negative (1455-1455), there are no real solutions for yy. This means there are no ordered pairs (x,y)(x, y) that satisfy the system of equations.