Passage on matrices

Consider a system of linear eqn in 3 variables:
a1x+b1y+c1z=d1
a2x+b2y+c2z=d2
a3x+b3y+c2z=d3
The system can be expressed by matrix eqn
a1 b1 c1 x d1
a2 b2 c2 y = d2
a3 b3 c3 z d3

If A is non singular matrix i.e detA≠0,then soln of abbove system can be found by X=A-1B
If A is singular matrix i.e detA=0,then system will have no unique solution if (adjA)B=0 and the system has no solution if (adjA)B≠0
Consider the following matrices and answer the questions that follow:
A=a 1 0
1 b d
1 b c

B=a 1 1
0 d c

U=f
g
h

V=a2
0
0

X=x
y
z

Q1The system AX=U has infinetly many soln if_______
Q2If AX=U has infinte soln then prove that BX=V has either infinite soln or no soln
Q3If AX=U has infinite soln then determine the condition at which BX=V is consistent.
Q4Assertion/Reason
A:If AX=U has infinite solution and cf≠0 then one solution of BX=V is (0,0,0)
R:If a system has infinite solution,then one solution must be trivial.

16 Answers

24
eureka123 ·

Hey someone help me out...........plzzzzzzzzzz[2]

11
Anirudh Narayanan ·

Involves Cramer's rule........but i don't remember it exactly

lAl=0 => something

lAl ≠0 => something else

33
Abhishek Priyam ·

if you forgot cramers or any other rule...

solve it like a layman... convert it to system of equations and solve it...as you used to do in 9th 10th class... no need for matrix concepts..if u are not comfortable with matrices...

11
Anirudh Narayanan ·

Q4, BX exists but has order 2x1......and V has order 3x1 [7]
So BX cannot b equal to V [7]

pls correct me if i'm wrong

11
Anirudh Narayanan ·

Someone pls correct me

11
Anirudh Narayanan ·

eureka, pls see my doubt (post #5).

1
suyashtaneja taneja ·

well its very easy

1
Philip Calvert ·

i think its MArtins rule ani not Cramers........

11
Anirudh Narayanan ·

Ricky Martin??? [3]

Btw, philip. Did u see my doubt da?

1
Philip Calvert ·

see your study material da i dont know what it means but i guess it can be used over here ??sry if mistaken..

you will understand see i also studied from that
btw how did you do in the all india test...

11
Anirudh Narayanan ·

No da. See my doubt #4

3
msp ·

something something anikkum matricesukkum

11
Anirudh Narayanan ·

hehe.............

machan neeye sollu da..... BX oda order 2x1 dhane. Aana V oda order 3x1 da

11
Anirudh Narayanan ·

Pls someone........In Q4

Order of B is 2x3

Order of X is 3x1

So order of BX is 2x1

But how can this matrix be equal to a matrix of order 3x1 ??

Bhaiya, atleast u clear my doubt[2][2]

62
Lokesh Verma ·

yes there is a mistkae.. dont worry :)

11
Anirudh Narayanan ·

So Q4, A is wrong. So automatically R has to be correct [3]

Eureka, pls see the question yaar. BX=V comes in Q2, 3 and 4. PLs see if there is any mistake in the book from which you took this problem from

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