{(-5,64), (2,1)}
linear equation: y = -9x + 19
quadratic equation: y = x² - 6x + 9
Substitute the y in the quadratic equation by the its value in the linear equation.
-9x + 19 = x² - 6x + 9
- 19 - 19 *subtract 19 to both sides
-9x = x² - 6x -10
+9x + 9x *add 9x to both sides
0 = x² + 3x - 10
0 = (x + 5) (x - 2) *Factor
Set each factor = 0 and solve
x + 5 = 0 ; x - 2 = 0
x = -5 ; x = 2
Find the corresponding value of y using the linear equation.
y = -9x + 19
x = -5 x = 2
y = -9(-5) + 19 y = -9(2) + 19
y = 45 + 19 y = -18 + 19
y = 64 y = 1
(-5,64) (2,1)
Check each value on each equation.
y = x² - 6x + 9
(-5,64) (2,1)
64 = (-5)² - 6(-5) + 9 1 = 2² - 6(2) + 9
64 = 25 + 30 + 9 1 = 4 - 12 + 9
64 = 64 1 = 1
y = -9x + 19
64 = -9(-5) + 19 1 = -9(2) + 19
64 = 45 + 19 1 = -18 + 19
64 = 64 1 = 1
{(-5,64), (2,1)}
