First, change y to the value of x in order to find the exact value of x. x + y = 4 y = 4 - x
Second, subtitute y with 4 - x from the first equation y = -x² + 2x + 4 4 - x = -x² + 2x + 4 move all terms to the left side x² - 2x - x + 4 - 4 = 0 x² - 3x = 0 x(x - 3) = 0 x = 0 or x = 3
Third, now we have 2 values of x. Find the value of y for each of x For x = 0 y = 4 - x y = 4 - 0 y = 4
For x = 3 y = 4 - x y = 4 - 3 y = 1
The solution is (0,4) and (3,1). The answer is option b
