Roman C. answered • 08/06/15

Masters of Education Graduate with Mathematics Expertise

Gregg O.

08/06/15

Janenett R.

asked • 08/06/15(a)a < 0, b<0

(b) a<0

(c) a<0, b> 0

(d) a<-b

i think I understand the question and my answer might be a but I'm not sure how to show my work

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Roman C. answered • 08/06/15

Masters of Education Graduate with Mathematics Expertise

Negative means less than 0 so the statement given is a+b < 0

Subtracting b from both sides gives a+b-b < 0-b which simplifies to a < -b which is choice (d)

Gregg O.

The key word in the problem statement is MUST. Choice (a) is not true for all cases in which a+b<0, while choice (d) is.

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08/06/15

Gwen R. answered • 08/06/15

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Two numbers, a and b, are added together and the sum is negative (less than zero). So ONE or BOTH NUMBERS must be negative. If a is negative, b can be either positive or negative. But maybe a is positive, and b negative? What if they are BOTH negative? Knowing this, which choice ALWAYS works? a

Michael J. answered • 08/06/15

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Lets try each case.

choice A states that you add two negatives. Adding two negative gives you a negative sum.

-2 + (-2) = -4

choice B states that a is negative. This can have flexibility because it means that b can be either positive or negative and has no restrictions.

-2 + (-3) = -5 ----> negative

-2 + 3 = 1 ------> positive

choice C states that a is positive and b is negative.

-2 + 3 = 1 sum is positive

choice D states that a is less than the negative value of b.

-5 + (-3) = -8 negative

-10 + (-6) = -16 negative

Just as Roman mentioned, choice D works, but so does choice A.

Mark M.

tutor

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08/06/15

Arthur D.

tutor

I agree with Mark M. The key wording is "... must be true." Answer a) does not have to be true for a+b to be negative.

Roman C. has it correct.

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08/06/15

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Michael J.

08/06/15