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Re: If t > 0, and s is the only value of x for which x2 + tx + 100 = 0, th [#permalink]
Expert Reply
nikitapal wrote:
Why E is not correct option?
For me option D and E both are correct. As it both satisfy the condition t>0.


is use the answer choices and in this case 20

s+t=20

s and t might be a bunch of different combinations such as

0+20=20

20+0=20

15+5=20

5+15=20

.................

Using s none of those values satisfy the equation above

Of course, the explanation provided by rx10 is the most efficient way to solve instead of trial and error or testing values

regards
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Re: If t > 0, and s is the only value of x for which x2 + tx + 100 = 0, th [#permalink]
Hi Carcass
Thanks for the response.
If we take value of s= -5 & T = 25 then it will satisfy each and every condition. And in this case s+t = 20.
Can you please check if i am missing anything.
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If t > 0, and s is the only value of x for which x2 + tx + 100 = 0, th [#permalink]
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Since s is the only solution x^2+tx+100=0 and t>0 the only solution must come s^2+ts+100=(s+t)^2=(s+10)^2=0

At this point clearly s=-10 to have zero on the LHS

s+t=-10+20=10

In fact above I said that testing values is tedious because when you have an equation like that ion the stem you cannot test ANY value

I hope now is clear
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Re: If t > 0, and s is the only value of x for which x2 + tx + 100 = 0, th [#permalink]
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