if (x,y) is a solution to the system of equations above and x > 0 what is the value of x?

Question

y-x^2 +2 = 9x
y = 4x + 4

What is the value of y in the solutions of the system of equations above?

8x-4y =7
5y - 4x = 10

Answer 1

for the first, use substitution , that is, replace the y in the first with the value of y of the 2nd

y-x^2 +2 = 9x
4x+4 - x^2 + 2 = 9x
-x^2 - 5x + 6 = 0
x^2 + 5x - 6 = 0
take over, you have a nice quadratic which factors.
remember x > 0 , so reject the negative x value

In the second pair, I would multiply the 2nd equation by 2 and then add them.
easy after that