Answer:
Step-by-step explanation:
Variance is the sum of squares of all items x from mean. i.e
Variance =
Being the sum of squares variance can never be negative irrespective of mean being negative.
Std deviation is the square root of variances. This will thus be less than variance if variance >1 other wise std deviation will be bigger than variance.
Hence option d is right.
There are two things you should do right away
Divide through by minus 3
Substitute another letter (say z) for x^2
Step One
-3x^4/-3 +27x^2/-3 + 1200/-3 = 0/-3
x^4 - 9x^2 - 400 = 0
Step 2
Let z = x^2
(x^2)^2 - 9(x^2) - 400 = 0
z^2 - 9z^2 - 400 = 0
Step 3
By factoring solve for z
(z - 25)(z + 16) = 0
z = 25
x^2 = 25
x = +/- 5
============
z + 16 = 0
z = - 16
x^2 = - 16
x = sqrt(-16)
x = +/- 4i
I've included a graph to show that the zeros are correct.
