GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
If the equation, kx^2+4x+(5-k)=0
[#permalink]
21 Jul 2019, 05:54
21 Jul 2019, 05:54
2
Bookmarks
00:00
Question Stats:
60% (01:29) correct
39% (02:12) wrong based on 33 sessions
Hide Show timer Statistics
If the equation, \(kx^2+4x+(5-k)=0\) has real roots, find the inequality followed by k?
A) \(k^2-5k+4>0\)
B) \(k^2-4k+5>0\)
C) \(k^2-5k+4<0\)
D) \(k^2-4k+5<0\)
E) \(k^2-4k+4<0\)
A) \(k^2-5k+4>0\)
B) \(k^2-4k+5>0\)
C) \(k^2-5k+4<0\)
D) \(k^2-4k+5<0\)
E) \(k^2-4k+4<0\)
Manager
Joined: 20 Jun 2019
Posts: 181
Given Kudos: 41
GRE 1: Q160 V161
GRE 2: Q165 V159
Re: If the equation, kx^2+4x+(5-k)=0
[#permalink]
10 Mar 2020, 23:29
10 Mar 2020, 23:29
Can someone please explain this?
Re: If the equation, kx^2+4x+(5-k)=0
[#permalink]
11 Mar 2020, 23:30
11 Mar 2020, 23:30
2
equation, kx2+4x+(5−k)=0
Remember the quadratic formula.
( -b +/- sqrt(b^2-4ac) ) / 2a = the roots
( -4 +/- sqrt(16-4k(5-k) ) / 2a =
( -4 +/- sqrt(16-20k+4k^2) / 2a =
Note that we only care about making sure
That the sqrt is positive so I’m only going to look at
That
16-20k+4k^2 > 0 when?
4(4-5k+k^2) > 0
4-5k+k^2 > 0
Which is the same as A.
Posted from my mobile device
Remember the quadratic formula.
( -b +/- sqrt(b^2-4ac) ) / 2a = the roots
( -4 +/- sqrt(16-4k(5-k) ) / 2a =
( -4 +/- sqrt(16-20k+4k^2) / 2a =
Note that we only care about making sure
That the sqrt is positive so I’m only going to look at
That
16-20k+4k^2 > 0 when?
4(4-5k+k^2) > 0
4-5k+k^2 > 0
Which is the same as A.
Posted from my mobile device
