4GMAT - GMAT Online Practice Test
 

GMAT Questions Mailing List - Y! Groups Algebra Arithmetic and Geometric Progressions Arithmetic Mean, Median, Mode, Deviation Inequalities Data Sufficiency Geometry Mensuration Number Systems Percentages Permutation and Combination, Probability Profit & Loss Quadratic Equations Ratio, Proportion, Variance Set Theory Simple & Compound Interest Speed, Time, Distance Work & Time, Pipes & Cisterns

Quadratic Equation - February 07, 2005

The Math Practice Question for the day is from the topic Quadratic Equation in Algebra.

Question
What is the highest integral value of 'k' for which the quadratic equation x2 - 6x + k = 0 have two real and distinct roots?

A. 9
B. 7
C. 3
D. 8
E. 12

The correct choice is (D) and the correct answer is 8.

Explanatory Answer
Any quadratic equation will have real and distinct roots if the discriminant D > 0

The discriminant of a quadratic equation ax2 + bx + c = 0 is given by b2 - 4ac

In this question, the value of D = 62 - 4*1*k

If D > 0, then 36 > 4k or k < 9.

Therefore, the highest integral value that k can take is 8.
Copyright 2004-06 4GMAT.COM, Test Catalyst (India) Private Limited - all rights reserved
GMAT™ and GMAC™ are registered trademarks of the Graduate Management Admission Council™. The Graduate Management Admission Council™ does not endorse, nor is it affiliated in any way with the owner or any content of this web site.