What are the solutions of the equation x4−10x2+9=0? Use u substitution. Group of answer choices

x = 3 and x = 1

x = 3i, x = -3i, x = i, x = -i

x = -3, x = 3, x = 1, and x = -1

x = -3 and x = -1

Step-by-step explanation:

X^4 - 10X^2 + 9 =0    This factors. It just looks odd.

(x^2 - 1)(x^2 - 9) = 0

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

x = 1 and x = - 1

x^2 - 9 = (x + 3)(x - 3) = 0

x = 3

x = -3

The correct answer is C (third one down).

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.

fwms@lil_ben06

step-by-step explanation: