basic maths

Question

Comments

answer will be D

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why it's D?? can you explain it.

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I think in option D , none of these should be written in place of can't be determined. Because

The values of x given in the options i.e. x=1,-1,-2 are not satisfy the above equation.

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X=-1is correct option

Answer 1

81 * (16/25)^(x+2)  + (3/5)^(2x+4) = 144           .....eq1

you can check option one by one in  

check option (A) put x=1 in eq 1      ,  we ll get    eq1 is not satisfied 

check option (B) put x= -1 in eq 1    ,  we ll get    eq1 is not satisfied 

check option (C) put x=-2 in eq 1     ,  we ll get    eq1 is not satisfied 

then   option (D) is correct                 ans