exponents question

Question

Hi,

I get that m = -3.

m^(-2) =  ( -3 ) ^(-2) ????????

say m=3
I thought the rule was, -m^(2) = -3^2 = -9 AND (-m)^2 = (-3)^2 = 9

kind of confused here. i got (C) btw....

fluke · Answer

m^{-1}=-\frac{1}{3}

\frac{1}{m^{1}}=-\frac{1}{3}

Invertendo:
 m^1=-3

m=-3

m^2=(-3)^2=9

Invertendo
 \frac{1}{m^2}=\frac{1}{9}

m^{-2}=\frac{1}{9}

Ans: "D"

yogesh1984 · Answer

Umm... let me try see Q asks for  m^-2  where we have got  m^-1  so multiply twice ehy go round-2 with other options here  -1/3 * - 1/3 = 1/9   D

Sudhanshuacharya · Answer

hi, i guess you missed to add (-2) as power to m
(m)^(-2) = (1/m^2)

replacing m as -3, we get (1/(-3)^2)
= 1/9

KarishmaB · Answer

When you replace a variable by a negative number, the negative sign is included. Say, you know m^2 = n . If m = -4, what is n? Replace the m by -4. Since m is squared, the entire -4 will be squared. (-4)^2 = n And you are right. -m^{2} = -3^2 = -9 AND (-m)^2 = (-3)^2 = 9 As for this question, Given: m^{-1} = -1/3 , I would just square both sides to get m^{-2} (m^{-1})^{2} = (-\frac{1}{3})^2 m^{-2} = 1/9 For more on exponents rules, check: https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2011/07 ... eparation/ https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2011/07 ... ration-ii/

vinayrsm · Answer

simple question, tricks your mind with reciprocals due to negative power!

386390 · Answer

Thank you very much!

nikhilsamuel89 · Answer

Square the expressions on both sides of the equation.
m^(-1) = -1/3
squaring,
(m^(-1))^2 = m^(-2) = 1/9 (since square of neg. no. = pos.)

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