In which of the following expressions does the "x" term have a coefficient of -1? 2x2+x−92 x squared plus x minus 9

3x2−x−53 x squared minus x minus 5

2x2−3x+12 x squared minus 3 x plus 1

x2+2x+7

idk

step-by-step explanation:

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

the answer is

a.

x = 42

y = 10

i got it down chief.