INDICES AND LOGARITHMIC NOTATIONS
English
ابتدایی
These questions are testing on the laws of indices and the laws of logarithmic notation. All logarithms are tested using base 10. The questions are very useful.
توضیحات
Mathematics, Algebra, Logarithms, Logarithmic notations, Indices, Addition, Multiplication, Subtraction, Division
تگها
32
سوال
5 دقیقه
به ازای سوال
16:06
زمان متوسط
4.0
امتیازات مسابقه
102
شرکتکننده
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In question 21, x = -6 can't be the answer because it's not in domain of log(x+5).... Log(-1) is not defined so -6 can't be counted as an answer..
Log(x+5) = log4 - log(x+2)
Right?
But if -6 if the answer then...
log(-1) = log4 - log(-4)
How will you define that?
Logarithm of NEGATIVE numbers is NOT DEFINED.
Domain of the equation is :
Log(x+5) →x≥ (-5)
Log (x+2) →x ≥(-2)
So, x can have values only between (-2, ∞), any value outside this interval is not defined.
( log(0) is also NOT DEFINED)
log A - log B = log (A/B)
X+5 = 4/(X+2)
When you cross multiply you end up with a Quadratic equation, and the value of X will be - 6 and - 1.