BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

minimum value

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 447
Joined: Sun Apr 19, 2009 9:08 pm
Location: Kolkata,India
Thanked: 7 times
GMAT Score:670

minimum value

by uptowngirl92 » Sat Sep 26, 2009 6:29 pm
What is the minimum value of the expression 2(x^2) + 3(y^2) - 4x - 12y + 18?
a) 18
b) 10
c) 6
d) 4
e) 0

Detailed explanations please!
Top
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 64
Joined: Sat Aug 01, 2009 3:13 am
Thanked: 5 times
Followed by:1 members
GMAT Score:740

Re: minimum value

by mohitsharda » Sat Sep 26, 2009 10:06 pm
uptowngirl92 wrote:What is the minimum value of the expression 2(x^2) + 3(y^2) - 4x - 12y + 18?
a) 18
b) 10
c) 6
d) 4
e) 0

Detailed explanations please!
Try to rework the expression:
2(x^2) + 3 (y^2) - 4x - 12y + 18
=> [2(x^2)- 4x] + [3(y^2) -12y] + 18
=> 2[(x^2)-2x] + 3 [(y^2) - 4y] + 18
=> 2[ (x-1)^2 -1] + 3[(y-2)^2 - 4] + 18
=> 2(x-1)^2 + 3 (y-2)^2 -2 - 12 + 18
=> 2 (x-1)^2 + 3(y-2)^2 + 4
Since min value of (x-1)^2 and (y-2)^2 is 0
the min value of the expression is 4.
MS
Top
Post new topic Post Reply
• Page 1 of 1