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MA
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JohnBussey
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Another one for B

(-a) ^ b will always be postive for an even value of b.
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rxs0005
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I get it now

Statement 1 could be + / -

B should be the correct answer
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it is b ?

1) not sufficient, because it depends wether b is even or odd
(-2)^-2 = 1/(-2)^2 = 1/4 => positive but (-2)^-3 = 1/(-2)^3 = - 1/8 => negative

2) sufficient (-2)^2 = 4 => positive and (-2)^-2 = 1/(-2)^2 = 1/4 => positive.

B
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MA
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JohnBussey
A negative exponent turns a number into a fraction. 5 ^ -2 = 1 / 5 ^ 2 = 1 / 25. But the fact that a number is a fraction is unrelated to whether that number is positive or negative. So statement 1 alone is no help.

An even exponent, on the other hand, always yields a positive number or zero. This is because the base number will be multiplied by itself an even number of times and any minus signs will all cancel out. (-3)^4 = -3 * -3 * -3 * -3 = (-3 * -3) * (-3 * -3) = 9 * 9 = 81.

So statement 2 is enough to assure us that, no, the expression can not yield a negative. The answer is B.


excellent explanation john. B is OA.



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