"Show that" terminology (1 Viewer)

[loje]

Quick question on the "show that" question.

The question is "Show that x = pi/6 is a solution of cot(x) = tan(2x).

The worked out solution from school basically they subbed x = pi/6 into cot(x) and then in tan(2x). Then they would equal, so it's a solution.

BUT I thought we are supposed to solve cot(x) = tan(2x) pretending we didn't know that pi/6 is a solution, as it's a "show that" question?

Thanks

 

[leehuan]

Quick question on the "show that" question.

The question is "Show that x = pi/6 is a solution of cot(x) = tan(2x).

The worked out solution from school basically they subbed x = pi/6 into cot(x) and then in tan(2x). Then they would equal, so it's a solution.

BUT I thought we are supposed to solve cot(x) = tan(2x) pretending we didn't know that pi/6 is a solution, as it's a "show that" question?

Thanks

Technically yes.

You sub it in if it says verify that.

But there are a ton of schools that don't know to use the word verify. I've found on many answers it's safe to assume the result

 

[InteGrand]

Quick question on the "show that" question.

The question is "Show that x = pi/6 is a solution of cot(x) = tan(2x).

The worked out solution from school basically they subbed x = pi/6 into cot(x) and then in tan(2x). Then they would equal, so it's a solution.

BUT I thought we are supposed to solve cot(x) = tan(2x) pretending we didn't know that pi/6 is a solution, as it's a "show that" question?

Thanks

 

[InteGrand]

Technically yes.

You sub it in if it says verify that.

But there are a ton of schools that don't know to use the word verify.
_________________

Of course, it's easy enough. It's just 1/tan(x) = 2tan(x)/(1-tan^2(x)) <=> 1-tan^2(x) = 2tan^2(x) assuming x can't equal pi/4 (which doesn't matter) <=> tan^2(x)=1/3

So in summary, the reason we can do the original Q. how the solutions did it is that we were basically already given the answer, rather than because of the choice of words in the question.

 

[loje]

Yeah I see, but my school usually tends to be particular with "show that" (must start from scratch) where as prove that (start from LHS or RHS).

I guess however because of the way they worded the question in that order (giving the answer first), it is probably good enough to just sub in the solution.

Especially since it is actually just 1 mark.

Thanks guys

 

[leehuan]

So in summary, the reason we can do the original Q. how the solutions did it is that we were basically already given the answer, rather than because of the choice of words in the question.

Found a trend where questions such that as (requires you to integrate a derivative, i.e. putting an operator in front of LHS and RHS) will never use the word verify anyway. Only show or prove