Answer:
a = -10
Step-by-step explanation:
-0.4a + 3 = 7
subtract 3 from each side
-0.4a + 3-3 = 7-3
-.4a = 4
Divide each side by -.4
-.4a/ -.4 = 4/-.4
a = - 10
To calculate the remaining caffeine, we use the radioactive decay formula which is expressed as An = Aoe^-kt where An is the amount left after t time, Ao is the initial amount and k is a constant we can calculate from the half-life information. We do as follows:
at half-life,
ln 1/2 = -k(6)
k = 0.12/hr
An = 80e^-0.12(14)
An = 15.87 mg
X-12 will give the other number
Answer:
we know
Step-by-step explanation:
Answer:
-15/2 or -7.5 or -7½
Negative StartFraction 15 Over 2 EndFraction
Step-by-step explanation:
Slope or gradient of a line is the ratio of change in y co-ordinates to the change in x co-ordinates.
Therefore;
M=∆y÷∆x
The change in y co-ordinates is given by
∆y=y2-y1
Similarly, change in x co-ordinates is given by
∆x=x2-x1
Given the two points as (5, 80) and (7, 65)
X1=5 Y1=80
X2=7 Y2=65
∆y=65-80=-15
∆x=7-5=2
Hence ∆y÷∆x will be -15÷2=-7.5 or -7½
Negative StartFraction 15 Over 2 EndFraction
