Answer:
x = 5/e
Step-by-step explanation:
ln x- ln 5= -1
We know that ln a - ln b = ln (a/b)
ln x- ln 5= -1
ln(x/5) = -1
Raise each side to the power of e
e^ ln(x/5) = e^-1
We know that e^-1 = 1/e
x/5 = 1/e
Multiply each side by 5
x/5 *5 = 1/e * 5
x = 5/e
Answer:
300 sq. cm.
Step-by-step explanation:
Do you need the explanation? If so, I can make one for you. You see, my hand is hurt, and it pains me to type.
Let be:Speed of the wind: WSpeed of the plane in still air: P
Against the wind the plane flew:Distance: d=175 milesTime: ta=1 hour 10 minutesta=1 hour (10 minutes)*(1 hour/60 minutes)ta=1 hour + 1/6 hourta=(6+1)/6 hourta=7/6 hourSpeed against the wind: Sa=d/taSa=(175 miles) / (7/6 hour)Sa=175*(6/7) miles/hourSa=1,050/7 miles per hourSa=150 mph
(1) P-W=Sa(1) P-W=150
The return trip only took 50 minutesDistance: d=175 milesTime: tr=50 minutestr=(50 minutes)*(1 hour/60 minutes)tr=5/6 hour
Speed retur trip: Sr=d/trSr=(175 miles) / (5/6 hour)Sr=175*(6/5) miles/hourSr=1,050/5 miles per hourSr=210 mph
(2) P+W=Sr(2) P+W=210
We have a system of 2 equations and 2 unknows:(1) P-W=150(2) P+W=210
Adding the equations:P-W+P+W=150+2102P=360Solving for P:2P/2=360/2P=180
Replacing P by 180 in equation (2):(2) P+W=210180+W=210
Solving for W:180+W-180=210-180W=30
Answers:The speed of the plane in still air was 180 mphThe speed of the wind was 30 mph
2.5x + 4x = 39
6.5x = 39
x = 39 / 6.5
x = 6
