I am going mixed

Asked Dec 09 '14 at 20:13

Active Dec 09 '14 at 21:13

Viewed 47 times

Why this is wrong ?

$ -1=(-1)^{2/2}=((-1)^{2})^{1/2}=1^{1/2}=1 $

Then

$1=-1$

asked Dec 09 '14 at 20:13

1

the folks at math.stackexchange will tell you $(-1)^{2/2}\neq((-1)^2)^{1/2}$ – QuantumDot Dec 09 '14 at 20:17
Why it is not equal. – Dec 09 '14 at 20:18
1^(1/2)=+/-1. you then take the -1 to match the LHS. – Basheer Algohi Dec 09 '14 at 20:19
$((a)^{m})^{n}=((a)^{n})^{m}$ – Dec 09 '14 at 20:19
Step 2 -> Step 3 is wrong. The Order of evaluation matters. – Chen Stats Yu Dec 09 '14 at 20:50
2

@YvesKlett And also for the title... :) – sebhofer Dec 09 '14 at 21:06
LOL the tags are awesome. – DumpsterDoofus Dec 09 '14 at 21:12
@Masoud The rule $(a^m)^n = a^{mn}$ is not true for all $a$, $m$, $n$. Generally when that rule is taught, these variables are assumed to be positive. – Greg Hurst Dec 09 '14 at 21:29
A closer post (instead of the linked one) is https://math.stackexchange.com/questions/547181 – Anne Bauval Dec 31 '24 at 16:44

0 Answers0