Question

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Answer 1

Answer:

2:- Let no. be x/y

A/Q,

x/y + 2/2 = 9/11

x + 2/y+2 = 9/11

11x +22 = 9y + 18

11x - 9y = 18 - 22

11x - 9y = -4 -------(1)

x +3/y+3 = 5/6

6x + 18 = 5y + 15

6x - 5y = 15 - 18

6x - 5y = -3 -----(2)

11x - 9y -6x + 5y = -4 +3

5x - 4y = -1

-4y = -1 -5x

-4y = -(1+5x)

4y = 1+5x

y = 5x + 1/4 ---(3)

Put in eq 1

11x - 9y = -4

11x -9(5x+1/4) = -4

11x - 45x -9/4 = -4

44x -45x -36/4 = -4

-x-36= -16

-(x+36) = -16

x + 36 = 16

x = 16-36 = -20 ans.

Put in eq 2

6x-5y = -3

-5y = -3 -6x

-5y = -3 -6 × -20

-5y = 117

y = -117/5 ans.

3:-

a=9;d=8:S=636

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

636 = n/2[2(9)+(n-1)8]

636 = n/2[18+8n-8]

636=n/2=[8n+10]

4n²+5n-636=0

4n²+(53-48)n-636=0

4n²+53n-48n-636=0

4n(n-12)+53(n-12)=0

(n-12) (4n+53)=0

no. of terns cannot be in fraction so we take this zeroes:

n-12=0

n=12 ans.

Answer 2

Answer:

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