Answer D because you want to get the x by itself and in order to do this she needs to multiply by -4 so that one side only has x.
Answer:
1.5 or -5
Step-by-step explanation:
2x²+7x-15=0
Divide by 2:
x²+7x/2-15/2=0
x=-7/2/2 ± √49/4(4)+15/2
=-7/4 ± √49/16+120/16
=-7/4± √169/16=-7/4 ±13/4
=6/4 or -20/4
=1.5 or -5
Use Math..way. Put in equation, hit solve, will give u val. for N
Dimensions of the room in cm = 2.54 x 12 by 15 x 2.54 by 2.54 x 8.5 = 30.48 by 38.1 by 21.59
Volume of the room in cubic cm = 30.48 x 38.1 x 21.59 cubic cm = 25,072.21 cubic cm
Given that the density of air at room temperature is

, thus the mass of air in the room = 25,072.21 x 0.00118 = 29.59 g = 0.0296 kg
Given that the lethal dose of HCN is approximately 300 mg HCN per kilogram of air when inhaled, thus the <span>amount of HCN that gives the lethal dose in the small laboratory room is given by 300 x 0.0296 =
8.88 mg.</span>