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Pranab Hari Dhar
Asked: 2022-11-05T17:37:58+05:30 In:

If the roots of equation `(a + 1)x^2-3ax + 4a = 0` (a is not equals to -1) are greater than unity, then
A. `[-(10)/(7),1]`
B. `[-(12)/(7),0]`
C. `[-(16)/(7),-1)`
D. `(-(16)/(7),0)`

If the roots of equation `(a + 1)x^2-3ax + 4a = 0` (a is not equals to -1) are greater than unity, then
A. `[-(10)/(7),1]`
B. `[-(12)/(7),0]`
C. `[-(16)/(7),-1)`
D. `(-(16)/(7),0)`
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  1. Correct Answer – C
    `(c )` `(a+1)x^(2)-3ax+4a=0`
    `D=9a^(2)-16a(a+1) ge 0` ………`(i)`
    `x_(1) gt 1`, `x_(2) gt 1`
    `:. (a+1)f(1) gt 0` and `(3a)/(2(a+1)) gt 1`
    `implies(a+1)(2a+1) gt 0`
    and `(a-2)/(a+1) gt 0` ……..`(ii)`
    `(2a+1)/(a+1) gt 0`………`(iii)`
    Solving `(i)`, `(ii)` and `(iii)`, we get `-(16)/(7) le a lt -1`.

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