I couldn't do it!

Q: Given a,b,c and d ε R satisfying a+b=8 ; ab+c+d=23 ; ad+bc = 28 ; cd = 12 , Find

a) a+b+c+d
b) ab+cd
c) ac+bd
d) ab

(It's matrix type but I didn't wrote the options as it was taking more time)

Q: The no. of values of ' k ' for which the expression is a perfect square , (2x2-4(k-1)x+3) (x2+2kx+k+1)

I got 0?

8 Answers

1
rishabh ·

for the first one,
a + b + c+d = 15
ab + cd = 28
ac + bd = 28
ab = 16

1
rishabh ·

is the second Ques no of "integral" values of k ?

1
buddyboyyash ·

for ur second question....there are 2 real values of k....bt 0 integral values...pls clarify if the question asks for integral values of k...

the 2 real values are....

"(2±√6)/2"

262
Aditya Bhutra ·

2nd one - k= 1/2 .

71
Vivek @ Born this Way ·

2nd one has 1. That I got later..

And for first one, I need a logical approach to solution. No Copy paste please. Cause I have a ridiculous one solution solution which completely not understandable to me

11
Devil ·

1) That's not enough rishabh, there is another answer to each of the 4 questions... I shall post my soln. if needed.

1
rishabh ·

could you please pst your method.
and also bhaiyya im prep for rmo this year. din write it last year..but tried the ppr @ home evn then got just 2.5 answers..please suggest me the material reqd. and do mail me any pdf/books you have regarding the same.
thanks.

71
Vivek @ Born this Way ·

@Soumik Bhaiya.. Yes Please post a ' logical + genuine ' solution to the above problem.

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