The height of a street light is 21 feet. It casts a 20−foot shadow. At the same time, a man standing next to the street light ca
sts a 5−foot shadow. How tall is the man? If needed, round the answer to the nearest hundredth.
2 answers:
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Please refer to my image where it shows my work as I’m explaining.
Okay, for system 1:
1. I am using the elimination method to solve. So I check if all the terms are lined up and if any are the same. I found that 2X are common in both equations.
2. The goal is to “eliminate” the term hence the name. So I can choose to add or subtract. I chose subtraction because 2 - 2 equals 0 which is our goal. Solve for the rest of the terms. This will lead to getting y =4. Refer to image for the work.
3. Last step to to find the X value. We do this by picking any of the given equations,then substitute y with 4 and solve to eventually get x = 10. Refer to image for the work.
FOR SYSTEM 2:
1. Again, I am using the elimination method to solve. I noticed that NONE of the terms are in common so I will have to intervene. You can chose any term to create a match with but I chose Y since it was the one I could use the smallest number to multiply with. When multiplying, DONT just multiply Y, multiply ALL the terms in the equation or else everything will crash.
2. Now that I have terms in common I can choose to add or subtract. I chose subtraction because 2-2 equals zero which is what we want. Solve look at image for my process which lead to X = -8
3. Last step is to find the value of Y. Chose any of the given equations in system 2 then substitute x with -8. Refer to image to see process. It lead to y = 20
To check the validity of the answers, substitute the x and y values into both equations both side of the equal side should have the same number. Hope that helped!
Okay, for system 1:
1. I am using the elimination method to solve. So I check if all the terms are lined up and if any are the same. I found that 2X are common in both equations.
2. The goal is to “eliminate” the term hence the name. So I can choose to add or subtract. I chose subtraction because 2 - 2 equals 0 which is our goal. Solve for the rest of the terms. This will lead to getting y =4. Refer to image for the work.
3. Last step to to find the X value. We do this by picking any of the given equations,then substitute y with 4 and solve to eventually get x = 10. Refer to image for the work.
FOR SYSTEM 2:
1. Again, I am using the elimination method to solve. I noticed that NONE of the terms are in common so I will have to intervene. You can chose any term to create a match with but I chose Y since it was the one I could use the smallest number to multiply with. When multiplying, DONT just multiply Y, multiply ALL the terms in the equation or else everything will crash.
2. Now that I have terms in common I can choose to add or subtract. I chose subtraction because 2-2 equals zero which is what we want. Solve look at image for my process which lead to X = -8
3. Last step is to find the value of Y. Chose any of the given equations in system 2 then substitute x with -8. Refer to image to see process. It lead to y = 20
To check the validity of the answers, substitute the x and y values into both equations both side of the equal side should have the same number. Hope that helped!
Answer:
Time spent rowing down stream
Speed of boat in still water
Step-by-step explanation:
Let speed of boat in still water be
Speed of current
Speed of boat down stream =
Distance rowed down stream = 2400 m
Time spent rowing down stream = =
Speed of boat up stream =
Distance rowed up stream =
Time spent rowing up stream =
We know that,
So,
Cross multiplying
Dividing both sides by
Adding 60 to both sides.
Subtracting both sides by
Dividing both sides by 5.
∴
Speed of boat in still water
Time spent rowing down stream =