Respuesta :

you need a number such that  it =  (half coefficient of x )^2

so for the first one: 1/2 * 2 = 1  ,   1^2 = 1   So answer is 1 

second:  1/2 * -20 = -10  , (-10)^2 = 100  

third one 1/2 * 5 = 2.5 and 2.5^2 = 6.25

Answer:

1,100,6.25

Step-by-step explanation: