Answer:
Solutions are 2, -1 + 0.5 sqrt10 i and -1 - 0.5 sqrt10 i
or 2, -1 + 1.58 i and -1 - 1.58i
(where the last 2 are equal to nearest hundredth).
Step-by-step explanation:
The real solution is x = 2:-
x^3 - 8 = 0
x^3 = 8
x = cube root of 8 = 2
Note that a cubic equation must have a total of 3 roots ( real and complex in this case). We can find the 2 complex roots by using the following identity:-
a^3 - b^3 = (a - b)(a^2 + ab + b^2).
Here a = x and b = 2 so we have
(x - 2)(x^2 + 2x + 4) = 0
To find the complex roots we solve x^2 + 2x + 4 = 0:-
Using the quadratic formula x = [-2 +/- sqrt(2^2 - 4*1*4)] / 2
= -1 +/- (sqrt( -10)) / 2
= -1 + 0.5 sqrt10 i and -1 - 0.5 sqrt10 i
Answer:
11.95 dollars
Step-by-step explanation:
Cost of one LED bulb = 6.95 dollars
Cost of changing one bulb = 3 dollars
Life of each bulb = 5 years.
In 10 years, only one time after 5 years the bulbs would have been changed
Hence cost of 100 lamps = 695 and
cost of changing once = 500
Total cost = 1195 dollars for 11 years
Divide this by 10 years to get average cost per year
Cost of 100 lamps per year = 1195/100 = 11.95 dollars
Step-by-step explanation:
4 and 5 is one 20/25
Answer:
Step-by-step explanation:
x ≈ 4.66667
Answer:
12
Step-by-step explanation:
