Question

How many solutions does the system have?
y = -3x +9
3y = -9x + 9

Answer 1

{y,x} = {0,1}

Explanation:

// Solve equation [1] for the variable y

[1] y = 3x - 3

// Plug this in for variable y in equation [2]

[2] -3•(3x-3) - 9x = -9

[2] - 18x = -18

// Solve equation [2] for the variable x

[2] 18x = 18

[2] x = 1

// By now we know this much :

y = 3x-3

x = 1

// Use the x value to solve for y

y = 3(1)-3 = 0