Tuesday, 14 February 2017

Algebra... Different "Faces" of Algebra (I)

The total length of 4 roads is (3x - 1) km.
What are the possible lengths of the 4 roads in kilometres?
Note that x is an integer.

e.g. The length of the 4 roads are: x km, x km, x-7 km, 6 km
Check: x + x + (x - 7) + 6 = 3x - 1

Enter your suggested lengths in comments.
You may also enter any assumptions you made to your answers.


  1. The answer above is correct, as x+x+x=3x and -7+6=-1. So, adding both together is 3x-1.

  2. Yes the answer above is correct =since -7+6=-1. And x+x+x=3x. Together the answer is (3x-1)

  3. Any length is possible assuming x is a real number

  4. x km - 1 km
    = x km - 7 km + 6 km
    This is because -7km + 6km = -1 km

  5. xkm, xkm, x-2km, 1km.

    I assumed that x-1 can be expressed as x-2+1, therefore, one of the roads will be x-2 and the other will be 1km. However, other combinations are ok as long as one road is x-y then the other road is y-1

  6. The answer is correct as:
    The answer is(3x-1)


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