As online attacks persist, spending on information security software continues to rise. The following table gives the forecast for the worldwide sales (in billions of dollars) of information security software through 2007 (x = 0 corresponds to 2002).

y = 10^9 (6.87 + 2.1(year-2002) )

Step-by-step explanation:

y = a + b x

x mean = 15/6 = 2.5

y mean = 72.7/6 = 12.12

x-x mean

-2.5 -1.5 -.5 +.5 +1.5 + 2.5

y - y mean

-6.12 -3.22 -.22 +1.88 +3.58 +4.08

(x - x mean)(y - y mean)

15.3 4.83 .11 .94 5.37 10.2

sum of those = 36.75

(x - x mean)^2

6.25 2.25 .25 .25 2.25 6.25

sum of those = 17.5

so

b = 36.75/17.5 = 2.1 agree with you

a = y mean - b x mean

= 12.12 - 2.1* 2.5 = 6.87 agree with you

y = 6.87 + 2.1 t

perhaps you used x in last line instead of t?

or

perhaps they want real years and billions

y = 10^9 (6.87 + 2.1(year-2002) )

1: -2 3/4, -2 1/2, -14, 0, 3, 8 1/3

2: -4, -3, -2 1/2, -2 1/4, 3 1/4,

step-by-step explanation:

center (1,3) with radius 6

step-by-step explanation:

we must complete the square to find the center and radius of the circle.

first make sure the x and y squared terms have 1 as their coefficients. we also make sure x and y terms together.

we now create space between the x and y terms with parenthesis.

we complete the square by taking the middle terms -2x and the -6y - divide each and square them.

we add the squares to both sides.

simplify.

and write the quadratics in factored form.

the center is (h,k) or (1,3). the radius is the square root of 36 which is 6.