Is m =1? 1)m^3=m 2)m^4=1

Question

Is m =1?
1)m^3=m
2)m^4=1

necromonger · Answer

(2) INSUFF because, for e.g. -1^4 = 1^4 =1
(1) m^3 = m*m^2 = m, so again -1 or 1 are probable, INSUFF

combining (1) and (2) m* (m ^3) = 1 => m* (m) = 1, again, -1 or 1 are possible.

(E)

haas_mba07 · Answer

Is m = 1?
1)m^3=m
 if m = 1 => yes, 
 if m = 13^(1/3) then m^3 = m => no,

=> Not sufficient
 
2)m^4=1
 if m = 1 => yes,
 if m = 7 => no, => Not sufficient

(1) & (2): 
 m^4 = m^3
or m^3(m-1) = 0

or m = 0 or m =1 Still not sufficient.

Answer: E

Zooroopa · Answer

Ans is  E  as m = +/-1 cannot be eliminated even after combining I and II.

Futuristic · Answer

Here's how I solved it:

1: m3 = m
=> m3 - m = 0
=>m(m-1)(m+1)=0

m = 0, 1, -1

So 1 is insufficient.

2: m4=1
=>m = 1, -1

So 2 is sufficient

Combining 1 and 2, m is 1,-1, so still sufficient, therefore E.

Is m =1? 1)m^3=m 2)m^4=1

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