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The value of b for which the equation 2(...

The value of `b` for which the equation `2(log)_(1/(25))(b x+28)=-(log)_5(12-4x-x^2)` has coincident roots is `b=-12` (b) `b=4orb=-12` `b=4orb=-12` (d) `b=-4orb=12`

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LHS
`2log_(1/25)(bx+28)2log_(5^(-2))(bx+28)`
LHS
`(2/-2)log_5(bx+28)=-log_5(bx+28)`
`log_5(bx+28)=-log_5(12-4x-x^2)`
`log_a^x=log_a^y`
`x=y`
`bx+28=12-4x-x^2`
...
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