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CBSE

Gujarati JEE Mathematics : શ્રેણિક

Multiple Choice Questions

41. જો $bold A bold space bold equals bold space open square brackets table row cell bold 3 bold a end cell bold b bold c row bold b cell bold 3 bold c end cell bold a row bold c bold a cell bold 3 bold b end cell end table close square brackets$ ; a,b,c ∈ R, abc = 1, AAT = 64 I અને |A| > તો (a³ + B³ + C³)³

343

Tips: -

અહીં A^T = A થાય.

A² = 64 I

|A|² = 64 ⇒|A| = 8

$bold vertical line bold A bold vertical line bold space bold equals bold space open vertical bar table row cell bold 3 bold a end cell bold b bold c row bold b cell bold 3 bold c end cell bold a row bold c bold a cell bold 3 bold b end cell end table close vertical bar$

= 3a[9bc - a²] - b[3b² - ca] + c[ab - 3c²]

|A| = 8 ⇒ 29abc - 3 (a³ + b³ + c³) = 8

a³ + b³ + c³ = 7

(a³ + b³ + c³)³ - 343

42. જો A = diag [3 2 1], તો ઍ-1 ના ઘટકોનો સરવાળો ......... છે.

$bold 1 over bold 6$
$bold 5 over bold 6$
$bold 11 over bold 6$
6

43.

જો સમીકરણ λx + 2y - 2z = I, 4x + 2λy - z = 2 અને 6x + 6y + λz = 3, નો અનન્ય ઉકેલ મળે તો,

λ#1
λ#2
λ#3
λ#-2

44.

bold A bold space bold equals bold space open square brackets table row bold 1 bold 3 row bold 3 bold 4 end table close square brackets bold space bold અન ે bold space bold A to the power of bold 2 bold space bold minus bold space bold 5 bold A bold space bold equals bold space bold kI bold space bold ત ો bold space bold space bold k bold space bold equals bold space bold. bold. bold. bold. bold. bold. bold. bold space

45.

bold જ ો bold space bold 2 bold space bold X bold space bold plus bold space open square brackets table row bold 1 bold 2 row bold 3 bold 4 end table close square brackets bold space bold equals bold space open square brackets table row bold 3 bold 8 row bold 7 bold 2 end table close square brackets bold space bold ત ો bold space bold X bold space bold equals bold space bold. bold. bold. bold. bold. bold. bold. bold space

$open square brackets table row bold 1 bold 3 row bold 2 cell bold minus bold 1 end cell end table close square brackets$
$open square brackets table row bold 1 cell bold minus bold 3 end cell row bold 2 cell bold minus bold 1 end cell end table close square brackets$
$bold 2 open square brackets table row bold 1 bold 3 row bold 2 cell bold minus bold 1 end cell end table close square brackets$
$bold 2 bold space open square brackets table row bold 1 cell bold minus bold 3 end cell row bold 2 cell bold minus bold 1 end cell end table close square brackets$

46. જો $bold A bold space bold equals bold space open square brackets table row cell bold minus bold 1 end cell cell bold minus bold 2 end cell cell bold minus bold 2 end cell row bold 2 bold 1 cell bold minus bold 2 end cell row bold 2 cell bold minus bold 2 end cell bold 1 end table close square brackets$ તો adj A = .......

3A^T
3A
A^T
A

47.

bold જ ો bold space bold A bold space bold equals bold space open square brackets table row bold 1 bold 1 row bold 0 bold 1 end table close square brackets bold comma bold space bold B bold space bold equals bold space bold. bold. bold. bold. bold. bold. bold. bold. bold space bold જ ે થ ી bold space bold space bold AB bold space bold equals bold space bold BA bold. bold space bold જ ્ ય ાં bold space bold B bold space bold # bold space bold 1 bold space

$open square brackets table row bold x bold x row bold 1 bold x end table close square brackets$
$open square brackets table row bold x bold y row bold 0 bold y end table close square brackets$
$open square brackets table row bold x bold y row bold 0 bold x end table close square brackets$
$open square brackets table row bold x bold x row bold y bold 0 end table close square brackets$