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if X is a negative integer
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01 Oct 2018, 15:59
01 Oct 2018, 15:59
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If \(x\) is a negative integer. Which of the following must be negative?
Indicate all possible values.
A. \(x+1\)
B. \(-x+1\)
C. \(x^{-1}\)
D. \(x^{3}\)
E. \(-5x\)
F. \(x^{2}\)
Indicate all possible values.
A. \(x+1\)
B. \(-x+1\)
C. \(x^{-1}\)
D. \(x^{3}\)
E. \(-5x\)
F. \(x^{2}\)
Re: if X is a negative integer
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13 Jan 2019, 09:28
13 Jan 2019, 09:28
2
Given that,
X is a negative integer.
Using the strategy of plugging numbers
If x=-1, A= 0
If x= -1, B=2
If x=-1, C= negative
If x= -1, D= negative
If x=-1, E= 5
If x=-1, F= 1
Hence, answer is C and D.
X is a negative integer.
Using the strategy of plugging numbers
If x=-1, A= 0
If x= -1, B=2
If x=-1, C= negative
If x= -1, D= negative
If x=-1, E= 5
If x=-1, F= 1
Hence, answer is C and D.
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Re: if X is a negative integer
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14 Jan 2019, 06:58
14 Jan 2019, 06:58
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sandy wrote:
If \(x\) is a negative integer. Which of the following must be negative?
Indicate all possible values.
A. \(x+1\)
B. \(-x+1\)
C. \(x^{-1}\)
D. \(x^{3}\)
E. \(-5x\)
F. \(x^{2}\)
Indicate all possible values.
A. \(x+1\)
B. \(-x+1\)
C. \(x^{-1}\)
D. \(x^{3}\)
E. \(-5x\)
F. \(x^{2}\)
The keyword here is MUST.
A. \(x+1\). This need not be negative. If x = -0.1, then x + 1 = -0.1 + 1 = 0.9 (which is positive). ELIMINATE
B. \(-x+1\). If x = -1, then -x + 1 = -(-1) + 1 = 1 + 1 = 2 (which is positive). ELIMINATE
C. \(x^{-1} = \frac{1}{x}= \frac{1}{negative}= negative\). KEEP
D. \(x^{3}\). ODD powers PRESERVE the sign of the base. Since the base (x) is NEGATIVE, and since 3 is ODD, we know that \(x^{3}\) must be negative. KEEP
E. \(-5x\). If x = -1, then -5x = -5(-1) = 5 (which is positive). ELIMINATE
F. \(x^{2}\). If x = -1, then \(x^{2} = (-1)^{2} = (-1)(-1) = 1\) (which is positive). ELIMINATE
Answer: C, D
Cheers,
Brent
