soumya1989 wrote:

If m is a negative integer and m³ + 380 = 381m, then what is the value of m?

A. -21

B. -20

C. -19

D. -1

E. None of the above

Here's one approach:

Given: m³ + 380 = 381m

Rearrange to get m's on one side to get: m³ - 381m = -380

Factor to get: m(m² - 381) = -380

At this point, it's probably easiest to just PLUG IN the answer choices.

HOWEVER, I'm going to skip answer choice A since 21 is NOT a factor of 380, and we already know that -380 = m(m² - 381), which means m must be a factor of 380

Let's start with answer choice B (-20)

Plug -20 into the equation to get: (-20)[(-20)² - 381] = -380

Evaluate: (-20)[400 - 381] = -380

Then...: (-20)[19] = -380

Works!!

Answer:

Cheers,

Brent

_________________

Brent Hanneson – Creator of greenlighttestprep.com

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