Can somebody help me solve this problem .

b = 40

Step-by-step explanation:

You want your discriminant to be zero because then you have exactly one solution.

Solve b²-4ac = 0

=>

b² - 4·400 = 0

b = ±√1600

so b=±40

but f(-20) also has to be 0

so b=40 remains as the solution

b = 40

Step-by-step explanation:

If x = - 20 is a zero of f(x) then f(- 20) = 0 , that is

(- 20)² - 20b + 400 = 0

400 - 20b + 400 = 0

800 - 20b = 0 ( subtract 800 from both sides )

- 20b = - 800 ( divide both sides by - 20 )

b = 40

from the figure we get,

the x axis shows   the months and,

the y-axis shows the number of satisfied customer.

each line or each cell in upward direction (y-axis) shows 500.

the appropriate scale for the y - axis is: -

a = 2000 customers

b = 4000 customers

c = 6000 customers

d = 8000 customers

e = 10000 customers

f = 12000 customers

g = 14000 customers

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis: