Question

18. Find the sum of first 20 terms of AP 3, 7, 11, 15
using the formule
2 *** 4-9. bence
19
Find the discriminant of the quadratic equation
find the nature of its roots
20. Find the distance between the points A (
S) and B
2, 11 ) by using
distance formula
21.
A box contains 28 bulbs of which 7 bulbs are defective, a bulb is draw
randomly from the box. Find the probability of picking a non detective
bulb​

Answer 1

Answer:

mark me as branliest your answer is here in the phato

Answer 2

Answer: the answer is 820 ;)

Step-by-step explanation :  AP : 3,7,11,15

a = 3 , d = 4 , n = 20

S20 = n/2 [ 2a + ( n-1)d ]

       = 20/2 [ 2 x 3 + (20 - 1 ) 4 ]

       =10 [ 6 + 19 x 4 ]

       =10 [ 6 + 76 ]

        = 10 x 82

        = 820

#### by poojitha

        10th class

         hyderabad  

                                          __  THE END __