Question

If 2 log (x + 3) = log 81, then the value of ‘x’ is​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

ANSWER

FORMULA

n log (x) = log (x) ^n

SOLUTION

2 log(x+3) = log 81

log (x+3) ^2 = log 81

take antilog to remove log

(x+3)^2 = 81

x^2 +6x +8 -81 = 0

x^2 +6x -72 = 0

x^2 +12 x -6x -72 = 0

x(x+12) -6(x+12) =0

(x-6) (x+12) =0

solve this equation by quadratic formula

we get

x = 6

x = -12 but x = -12 is not possible because if we put x = -3 in log then it become negative as

-12+3 = -9

and log for negative numbers is not defined

so

x = 6

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