Answer:






let me know if you need an explanation.
The series in the form of arithmetic progression
The notation of A.P is a, a+d, a+2d.....
The summation notation is â‘
In this series a=3, d=7
Then the summation of A.P is â‘ = n/2(2a+(n-1)d)
=18/2(2*3+ (18-1)7)
= 9(6+17(7))
=9(6+119)
=9(125)
= 1125
Hence the total number of beads is 1125
Answer:
hieght at left is 24+1
and right is 25 both are equal now so h=25
base=8
area of triangle 1/2×b×h
1/2×8×25=100
16x²-49=
(4x)²-7²=
(4x-7)(4x+7)
Here I have used the expression:
a²-b²=(a-b)(a+b)