The answer is 8i.
i = √(-1)
√(-64) = √((-1) * 64)
= √(-1) * √64
= i * √8²
= i * 8
= 8i
2x^3y+18xy-10x^2y-90y
= 2xy(x^2 + 9)- 10y(x^2 + 9)
= (x^2 + 9)(2xy - 10y)
= (x^2 + 9) 2y(x - 5)
= 2y (x^2 + 9) (x - 5)
For example:
x+2y=7
6x+7y=2
__________
x=7-2y *
6*(7-2y)+7y=2 **
__________
x=7-2y
42-12y+7y=2
__________
x=7-2y
-5y=-40
__________
x=7-2y
y=8
x=-9
To figure out how much she spent all we have to do is add up $0.85, $4.50 and $1.50
$0.85 + $4.50 + $1.50 = $6.85
Therefore she spent $6.85
Hope this helps
So.. in this case, the starting amount is the 500mg sample... and the rate of decay, negative rate, is 1%, and at the time, the elapsed days is 0, to t = 0, P = 400
