Answer: ab =6
have:
=> a + b + 1 = ab
⇔ a + b + 1 - ab = 0
⇔ b - 1 - a(b - 1) + 2 = 0
⇔ (b - 1)(1 - a) = -2
because a and b are postive integers => (b - 1) and (1 - a) also are integers
=> (b - 1) ∈ {-1; 1; 2; -2;}
(1 -a) ∈ {-1; 1; 2; -2;}
because (b -1).(1-a) = -2 => we have the table:
b - 1 -1 1 2 -2
1 - a 2 -2 -1 1
a -1 3 2 0
b 0 2 3 -1
a.b 0 6 6 0
because a and b are postive integers
=> (a;b) = (3;2) or (a;b) = (2;3)
=> ab = 6
Step-by-step explanation:
Answer:
Area of Rectangle A
Area of Rectangle B
Fraction
Step-by-step explanation:
From the attached, we understand that:
The dimension of rectangle A is 2x by 2x
The dimension of rectangle B is x by 2x
Area of rectangle is calculated as thus;
Area of Rectangle A
Area of Rectangle B
Area of Big Rectangle
The largest rectangle is formed by merging the two rectangles together;
The dimension are 3x by 2x
The Area is as follows
The fraction of rectangle A in relation to the largest rectangle is calculated by dividing area of rectangle A by area of the largest rectangle;
Simplify
Answer: 119,616
You may have to erase the comma when inputting the answer.
=======================================================
Explanation:
The author sells 21,000 books in the first month.
Then they sell 21,000*(1-0.12) = 21,000*(0.88) = 18,480 in the second month.
Then they sell 18,480*(1-0.12) = 18,480*(0.88) = 16,262.4 = 16,262 in the third month.
And so on. These values follow a geometric sequence with first term a = 21,000 and common ratio r = 0.88
We can think of the 0.88 as 88% of the original value (since losing 12%, we keep the remaining 88%)
-------------
Use the formula below to sum the first 9 terms of the geometric sequence
Plug in a = 21000 and r = 0.88
The author sold about 119,616 books over the course of the first nine months.