1.

Let `f(x) = log (1-x) +sqrt(x^(2)-1). `Then dom (f )=?A. `(1,oo)`B. `(-oo,-1]`C. `[-1,1]`D. `(0,1)`

Answer» Correct Answer - B
let `f(x) =g(x) =h (x) " where " g(x) =" log " (1-x) "and " h(x) =sqrt(x^(2)-1)`
g (x) is defined only when `1-x gt 0 rArr x lt 1` So, dom (g) `=(-oo,1)`
h(x) is defined only when `x^(2) -1 ge 1 0 rArr 1 " or " x le -1`
`:. " dom " (h)= (-oo ,-1] uu [1,oo)`
`:. " dom (f ) = " dom " (f ) nn" dom " (h)= (-oo,1]`


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