What number must add to the expression below to complete the square x^2-x A.-1/2
B. 1/2
C. -1/4
D. 1/4

Option D is correct.

1/4 completes the square.

Step-by-step explanation:

To complete the square for a quadratic function, we require a third term that will enable the solutions of the quadrstic equation to be 2 repeated roots.

For that to be so for the quadratic equation

ax² + bx + c = 0,

b² has to be equal to 4ac

For this question, x² - x + c

From b² = 4ac

c = (b²/4a)

a = 1

b = -1, b² = 1

c = ?

c = (1/4)

Hence, (1/4) is the number that must be added to the expression to complete the square.

Hope this Helps!!!

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18