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Question Number 115508 by bemath last updated on 26/Sep/20

If determinant (((a    a^2        1+a^3 )),((b    b^2        1+b^3 )),((c    c^2        1+c^3 )))= 0  a≠b≠c → { ((a =?)),((b=? )),((c=?)) :}

If|aa21+a3bb21+b3cc21+c3|=0abc{a=?b=?c=?

Answered by bobhans last updated on 26/Sep/20

⇒ determinant (((a    a^2     1)),((b    b^2     1)),((c    c^2     1)))+  determinant (((a   a^2     a^3 )),((b    b^2    b^3  )),((c    c^2    c^3 )))= 0  ⇒(−1) determinant (((1   a^2     a)),((1   b^2     b)),((1   c^2    c)))+ abc determinant (((1   a   a^2 )),((1   b    b^2 )),((1   c   c^2 )))= 0  ⇒(−1)^2  determinant (((1    a    a^2 )),((1    b     b^2 )),((1    c    c^2 )))+ abc  determinant (((1    a    a^2 )),((1    b     b^2 )),((1    c     c^2 )))= 0  ⇒(1+abc)  determinant (((1    a    a^2 )),((1    b    b^2 )),((1    c    c^2 )))= 0  ⇒(1+abc)  determinant (((1           a             a^2 )),((0          b−a    b^2 −a^2 )),((0         c−a     c^2 −a^2 )))= 0  ⇒(1+abc)  determinant (((b−a        b^2 −a^2 )),((c−a       c^2 −a^2 )))= 0  ⇒(1+abc)[(b−a)(c−a)(c+a)−(c−a)(b−a)(b+a)]=0  ⇒(1+abc)(b−a)(c−a) [ c+a−b−a] = 0  (1+abc)(b−a)(c−a)(c−b) = 0   since a≠b≠c ; so we get abc = −1   let a = k , b = l → c = −(1/(k.l))

|aa21bb21cc21|+|aa2a3bb2b3cc2c3|=0(1)|1a2a1b2b1c2c|+abc|1aa21bb21cc2|=0(1)2|1aa21bb21cc2|+abc|1aa21bb21cc2|=0(1+abc)|1aa21bb21cc2|=0(1+abc)|1aa20bab2a20cac2a2|=0(1+abc)|bab2a2cac2a2|=0(1+abc)[(ba)(ca)(c+a)(ca)(ba)(b+a)]=0(1+abc)(ba)(ca)[c+aba]=0(1+abc)(ba)(ca)(cb)=0sinceabc;sowegetabc=1leta=k,b=lc=1k.l

Commented by bemath last updated on 26/Sep/20

gave kudos

gavekudos

Answered by TANMAY PANACEA last updated on 26/Sep/20

 determinant ((a,a^2 ,1),(b,b^2 ,1),(c,c^2 ,1))+ determinant ((a,a^2 ,a^3 ),(b,b^2 ,b^3 ),(c,c^2 ,c^3 ))=0   determinant ((a,a^2 ,1),(b,b^2 ,1),(c,c^2 ,1))+abc determinant ((1,a,a^2 ),(1,b,b^2 ),(1,c,c^2 ))=0   determinant ((1,a,a^2 ),(1,b,b^2 ),(1,c,c^2 ))+abc determinant ((1,a,a^2 ),(1,b,b^2 ),(1,c,c^2 ))=0  D+abc×D=0  D(1+abc)=0  D≠0   so abc=−1  let a=k   b=(1/k)   c=−1  i have just tried...

|aa21bb21cc21|+|aa2a3bb2b3cc2c3|=0|aa21bb21cc21|+abc|1aa21bb21cc2|=0|1aa21bb21cc2|+abc|1aa21bb21cc2|=0D+abc×D=0D(1+abc)=0D0soabc=1leta=kb=1kc=1ihavejusttried...

Commented by bemath last updated on 26/Sep/20

gave kudos sir.

gavekudossir.

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