Solving linear equation help! Dont know how to start problem

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agcustoms

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Can anyone help me with this problem?

Given:


A person cuts a rope into two pieces that are equal in length. The first piece is 4 times the length of the person’s forearm minus 1 inch. The second piece is 3 times the length of the person’s forearm plus 15 inches.


Task:


1. Construct the linear equation that represents the situation in the given using x as the variable for the person’s forearm.


2. Solve the linear equation you constructed both algebraically and graphically to find the length of the person’s forearm. Show your work.


3. Briefly discuss whether or not your answer is reasonable.
 
Assume the ropes are cut into lengths "L" inch

Assume the length of the persons forarm = x inch

Then

The first condition

The first piece is 4 times the length of the person’s forearm minus 1 inch

gives you

L = 4*x - 1.................................................(1)

This is your first equation,

Similarly, write the next equation - using the second condition.

Then solve for 'A'.

If you are still stuck, write back showing your work.
 
Re: Solving linear equation help! Dont know how to start pro

agcustoms said:
Can anyone help me with this problem?

Given:


A person cuts a rope into two pieces that are equal in length. The first piece is 4 times the length of the person’s forearm minus 1 inch. The second piece is 3 times the length of the person’s forearm plus 15 inches.


Task:


1. Construct the linear equation that represents the situation in the given using x as the variable for the person’s forearm.


2. Solve the linear equation you constructed both algebraically and graphically to find the length of the person’s forearm. Show your work.


3. Briefly discuss whether or not your answer is reasonable.
Click to expand...

Let x = length of the forearm in inches

One piece of the rope is equal to 4 times the forearm length, minus one inch. So that piece has a length of 4x - 1

The other piece is 3 times the forearm length, plus 15 inches. So that piece has a length of 3x + 15

You're told that the two pieces are equal.

So.....

4x - 1 = 3x + 15

Solve that for x.
 
So I am lost, all I need to do is solve for x? That seems to simple! i'm lost.
 
I'll show you another problem

solve for 'x' when

3x + 3 = x + 5

Isolate variables

3x + 3 - x = x + 5 - x

2x + 3 = 5

Isolate numbers

2x + 3 - 3 = 5 - 3

2x = 2

Isolate numbers again

2x/2 = 2/2

x = 1

check

3x + 3 = x + 5

3*1 + 3 = 1 + 5

6 = 6 .............checks
 
agcustoms said:
So I am lost, all I need to do is solve for x? That seems to simple! i'm lost.
Click to expand...

I'm sorry....if you are "lost" trying to solve an equation like

4x - 1 = 3x + 15

then you probably need to ask your teacher for some extra help.
 
Ok. I got this. Is this right? Can anyone I point me in the right path to answer C?

A. Construct the linear equation that represents the situation in the given using x as the variable for the person’s forearm.
Let x = length of the forearm in inches

One piece of the rope is equal to 4 times the forearm length, minus one inch. So that piece has a length of 4x - 1

The other piece is 3 times the forearm length, plus 15 inches. So that piece has a length of 3x + 15

You're told that the two pieces are equal.

So.....

4x - 1 = 3x + 15


B. Solve the linear equation you constructed both algebraically and graphically to find the length of the person’s forearm. Show your work.

4x-1=3x+15 original equation

4x-1-3x=15 subtract 3x from both sides

4x-3x=16 add 1 to each side and subtract 3 from 4

x=16


C. Briefly discuss whether or not your answer is reasonable.

Need help on this one
 
agcustoms said:
C. Briefly discuss whether or not your answer is reasonable.
Need help on this one
Click to expand...

Forearm = distance between elbow and wrist; mine's about 11 inches;
so 16 inches must be for 7 feet plus basketball players!

"One piece of the rope is equal to 4 times the forearm length, minus one inch. So that piece has a length of 4x - 1"

4(16) - 1 = 63

"The other piece is 3 times the forearm length, plus 15 inches. So that piece has a length of 3x + 15"

3(16) + 15 = 63

So not only is it reasonable, it is guaranteed correct :idea:
 
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