Area of a rectangular barnyard: A=6x^2+7x-20
A=6(6x^2+7x-20)/6
A=[(6^2)(x^2)+7(6x)-120]/6
A=[(6x)^2+7(6x)-120]/6
A=(6x+15)(6x-8)/6
A=(6x+15)(6x-8)/[(3)(2)]
A=(6x/3+15/3)(6x/2-8/2)
A=(2x+5)(3x-4)
A=bh
b=2x+5; h=3x-4
Answer: The possible dimensions of the barnyard are 2x+5 and 3x-4
Given:
The sum of two terms of GP is 6 and that of first four terms is 
To find:
The sum of first six terms.
Solution:
We have,


Sum of first n terms of a GP is
...(i)
Putting n=2, we get


...(ii)
Putting n=4, we get



(Using (ii))
Divide both sides by 6.
Taking square root on both sides, we get

Case 1: If r is positive, then using (ii) we get
The sum of first 6 terms is




Case 2: If r is negative, then using (ii) we get
The sum of first 6 terms is




Therefore, the sum of the first six terms is 7.875.
Answer:
Let x be odd such that LCM {x,40} = 1400 .
Since 1400 = 23×52×7 , then
x ∈ {5m×7n∣(m,n) ∈ {0,1,2}×{0,1}} .
By testing these values, we find that x = 175 .
3, 6, 9, 12,15, 18, 21, 24
8, 16, 24
Marco will fill up his car with gas and wash it on the 24th day.