wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

If x2 + y2 + xy = 1 and x + y = 2, then xy =

(a) –3

(b) 3

(c) -32

(d) 0

Open in App
Solution

Given:x2+y2+xy=1 ...1x+y=2 ...2Now,x+y=2Squaring both sides, we getx+y2=22x2+y2+2xy=4 Using the identity: a+b2=a2+b2+2abx2+y2+xy+xy=41+xy=4 From 1xy=4-1xy=3Hence, the correct option is b.

flag
Suggest Corrections
thumbs-up
41
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
(x+a)(x+b)
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon