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z^2+2z-15=0
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09 Nov 2020, 12:00
09 Nov 2020, 12:00
Expert Reply
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Question Stats:
82% (00:32) correct
17% (00:32) wrong based on 85 sessions
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\(z^2+2z-15=0\)
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Source: 320 GRE Math Questions
Quantity A |
Quantity B |
\(z^2\) |
\(20\) |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Source: 320 GRE Math Questions
Re: z^2+2z-15=0
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09 Nov 2020, 19:57
09 Nov 2020, 19:57
2
the roots of the equation are: -5 and 3
squaring them we get 25 and 9.
25>20 and 9<20
so the right answer is D
squaring them we get 25 and 9.
25>20 and 9<20
so the right answer is D
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Re: z^2+2z-15=0
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14 Nov 2020, 06:40
14 Nov 2020, 06:40
1
Carcass wrote:
\(z^2+2z-15=0\)
Quantity A |
Quantity B |
\(z^2\) |
\(20\) |
Given: \(z^2+2z-15=0\)
Back to the left side to get: \((z+5)(z-3)=0\)
Solve: \(z = -5\) OR \(z = 3\)
Let's examine both cases:
case i: \(z = -5\)
We get:
QUANTITY A: \(z^2 = (-5)^2 = 25\)
QUANTITY B: 20
In this case, Quantity A is greater
case ii: \(z = 3\)
We get:
QUANTITY A: \(z^2 = 3^2 = 9\)
QUANTITY B: 20
In this case, Quantity B is greater
Answer: D
