Question

Hola, Plz help me to solve this one ASAP!

Q)4)i)


Chapter: Arithmetic Progressions, class X, ICSE


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Answer 1

Answer:

1) n=16, S16= 440

2) not visible.

3)a= -35/3, a9= 85/3

4) not visible.

5)d=6

Step-by-Step Explanation:

1)a=5, d=3, an=50..

an= a+(n-1)d

50= 5+(n-1)3

50-5=(n-1)3

45/3=n-1

15=n-1

n=16

Sn= n/2( a+ an)

S16= 16/2(5+50)

S16= 8(55)

S16= 440

2) is not visible...

3) d=5, S9=75

Sn= n/2(2a+ (n-1)d)

S9= 9/2(2a + (9-1)5)                    

75= 9/2(2a+40)

75*2/9= 2a+40

150/9= 2a+40

50/3=2(a+20)

50/6= a+20

25/3= a+20

25/3-20=a

LCM= 3

25/3-60/3=a

-35/3=a

 a9= -35/3+8*5= -35/3+40= -35/3+120/3= 85/3

4) not visible...

5) a=3, n=8 and S= 192

Sn= n/2( 2a+ (n-1)d)

192= 8/2(6+(8-1)d)

192*2/8= 6+7d

24*2=6+7d

48=6+7d

42=7d

42/7=d= 6

d=6