The answer is -7 hope this helps!
2x+15x you can just switch the two.
Answer:
roots : 4, -4, i, -i
Step-by-step explanation:
This gets a bit tricky.
We have to substitude x^2 as u in this problem.
Now to rewrite x^4 − 15x^2 − 16 = 0 with u, we get
u^2 - 15u - 16 = 0
( u - 16) (u + 1)
U = 16
U = -1
<em>This is not the end of the problem. </em>
Now we have to substitute x^2 back to u.
x^2 = 16 --> we get the roots 4 and -4
x^2 = -1 --> we get the roots i and -i
tadah!
<span>x> -4 means that it is needed to find all the values that are greater than -4 "not including" -4 ... for negative values as you get from zero the values decrease which means that -8 is less than -7 and -7 is less than -6 etc.. and positive values are trivially known to be greater than negative ones then take each value and compare it with -4 -8 is less than -4 -4.3 is less than -4 -4 is equal to -4 which is not included in our required range which is x>-4 -3.8 is greater than -4 which will get in our solution 1.2 is greater than -4 3 is also greater than -4 So our final solution will be {-3.8,1.2,3} Which is B in our question Hope this helps :) Let me know too if you got it :) </span><span>
</span>Answer: C. {-3.8, 1.2, 3}
