An evergreen nursery usually sells a certain shrub after 9 years of growth and shaping. The growth rate during those 9 years is approximated by dh/dt = 1.8t + 3,
where t is the time (in years) and h is the height (in centimeters). The seedlings are 10 centimeters tall when planted (t = 0).
(a) Find the height after t years.
h(t) =
(b) How tall are the shrubs when they are sold?
cm

(a) After t years, the height is

18t² + 3t + 10

(b) The shrubs are847 cm tall when they are sold.

Step-by-step explanation:

Given growth rate

dh/dt = 1.8t + 3

dh = (18t + 3)dt

Integrating this, we have

h = 18t² + 3t + C

When t = 0, h = 10cm

Then

10 = C

So

(a) h = 18t² + 3t + 10

(b) Because they are sold after every 9 years, then at t = 9

h = 18(9)² + 3(9) + 10

= 810 + 27 + 10

= 847 cm

-3/2 ±1/2 sqrt(5) = x

Step-by-step explanation:

f(x) = 2x^2 + 6x + 2

Set the function equal to 0

0 = 2x^2 + 6x + 2

Factor out 2

0 = 2(x^2 + 3x + 1)

Divide by 2

0 = (x^2 + 3x + 1)

Subtract 1 from each side

-1 = x^2 +3x

Complete the square by dividing the x coefficient by 2 and then squaring

(3/2)^2 = 9/4

-1 +9/4 = x^2 +3x+9/4

-4/4+9/4 = (x+3/2) ^2

5/4 = (x+3/2) ^2

Taking the square root of each side

± sqrt(5/4) = sqrt( (x+3/2) ^2)

±1/2 sqrt(5) =  (x+3/2)

Subtract 3/2 from each side

-3/2 ±1/2 sqrt(5) = x