John sent a telegram of 44 words and he was charged shilling 25 for the first ten words and shilling 30 for each extra word .How
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Two main facts are needed here:
1. The logarithm , regardless of the base of the logarithm, exists for
.
2. The square root exists for
.
(in both cases we're assuming real-valued functions only)
By (2) we know that exists if
, or
.
By (1), we know that exists if
, or
. But as long as the square root exists, it will always be positive, so this condition will always be met.
Ultimately, then, we only require , so the function has domain
.
To determine the range, we need to know that, in their respective domains, and
increase monotonically without bound. We also know that
at minimum, at which point the square root term vanishes, so the least value the function takes on is
. Then its range would be
.
Let us assume last year the price of the item = $x.
After increase in price by 15% the new price = x + 15% of x = x+ 0.15x = 1.15x.
There is a 25% discount for employee.
25% of 1.15x = 0.25 × 1.15x = 0.2875 x.
Price after discount = 1.15x - 0.2875 x = 0.8625x.
The employee pays $172.50.
Therefore,
0.8625x = 172.50.
Dividing both sides by 0.08625.