A student begins to solve the problem:
sinxtanx=sinx
by writing tanx=1 as her first step.
Identify the error she has made in her reasoning and write down the correct first step she should have taken in solving the problem and give the equations that would need to be solved in order to solve the original problem.

Question

A student begins to solve the problem:
sinxtanx=sinx
by writing tanx=1 as her first step.
Identify the error she has made in her reasoning and write down the correct first step she should have taken in solving the problem and give the equations that would need to be solved in order to solve the original problem.

trojanpoem · Answer

sinxtanx - sinx = 0

sinx(tanx-1) = 0

either sinx = 0

or tanx = 1

4meisu · Answer

What was the error that she made in making that first step?

hartnn · Answer

the error that she made was that she cancelled out sin x
without even considering that sin x could be 0 !

4meisu · Answer

Oh, awesome! Thanks everyone :3 So quick and helpful