The speed of the stream: v s = 1 mph
v - David`s speed in still water
( v - 1 ) t 1 = 3
( v + 1 ) t 2 = 3
t 1 + t 2 = 4
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t 2 = 4 - t 1
3 = ( v - 1 ) * t 1
3 = ( v + 1 ) * ( 4 - t 1 )
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3 = v t 1 - t 1
+
3 = 4 v - v t 1 + 4 - t 1
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6 = 4 v + 4 - 2 t 1
2 = 4 v - 2 t 1
2 t 1 = 4 v - 2 / : 2 ( divide both sides of equation by 2)
t 1 = 2 v - 1
t 2 = 5 - 2 v
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3 = ( v - 1 ) * ( 2 v - 1 )
3 = 2 v² - 3 v + 1
2 v² - 3 v - 2 = 0
v 1/2 = 3+/- √(9 + 16 ) / 4 = (3 + 5)/4 = 8/4 = 2 ( other solution is negative )
Answer: David`s speed in still water is 2 miles per hour.
Mean, or average.
The mean is 5.625
Answer:
x= -7, y= -5 and
x= 2, y= 13
This may also be written as (-7, -5) and (2, 13).
Step-by-step explanation:
Start by labelling the two given equations:
y= x² +7x -5 -----(1)
2x -y= -9 -----(2)
Let's solve by substitution!
Making y the subject of formula in equation (2):
From (2): y= 2x +9 -----(3)
Substitute (3) into (1):
2x +9= x² +7x -5
x² +7x -5 -2x -9= 0
x² +5x -14= 0
Factorise:
(x +7)(x -2)= 0
x +7= 0 or x -2= 0
x= -7 or x= 2
Find the respective values of y.
Substitute into (1):
y= (-7)² +7(-7) -5 or y= (2)² +7(2) -5
y= 49 -49 -5 or y= 4 +14 -5
y= -5 or y= 13
Thus, the solutions are (-7, -5) and (2, 13).
Hello :
<span>-1.5+k=8.2
k=8.2+(+1.5)..... (+ 105 no : - )
k=.....</span>
Answer:
The length of the long side of the rectangle is 38 ft.
Step-by-step explanation:
If we test out all possible factors, we will see that 15 x 38 is the most fitting.
Perimeter: 15 + 15 + 38 + 38 = 106 ft.
Area: 15 x 38 = 570 square ft.
38 ft. is the measurement of the long side and 15 ft. is the measurement of the smaller side.