The best and most correct answer among the choices provided by your question is the second choice or letter B "20".
The current area is 120(80)=9600 and he want to expand it by 4400 so that the new area will be 9600+4400=14000
14000=(120+x)(80+x)
14000=9600+200x+x^2
x^2+200x-4400=0
x^2-20x+220x-4400=0
x(x-20)+220(x-20)=0
(x+220)(x-20)=0, since x is an increase it must be greater than zero so
x=20ft
(120+20)(80+20)=14000ft^2
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Theres only 4 but the answer is -15
<span>Answer:
MgF2 ====⇒ Mg+2 + 2F-
Ksp = [Mg+2][F-]^2
Let S = molar solubility of MgF2
[Mg+2] = S ; [F-] = 2s
Since the [F-] is initially 0.40 M, then [F-] = 0.40 + 2S
6.4 x 10^-9 = (S) (0.40 + 2S)^2 ; one can neglect the 2S in the 0.40 + 2S expression since it is very, very small compared to the 0.40 already present.
6.4 x 10^-9 = S(0.40)^2
S = 4.0 x 10^-8
Molar solubility = 4.0 x 10^-8</span>
Answer: The first one is = 27.5
1/3 * 25 * 3.3 = 27.5
