Question

15 + 20 + dash = 20+25+15​

Answer 1

Answer:

This is an

Arithmetic sequence

The standard sequence being :

a , a+d , a+2d , a+3d , ............... , a+(n-1)d

where a , is the 1st term and d , the common difference.

The sum to n terms of the sequence is :

∣

∣

∣

∣

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

S

n

=

n

2

[

2

a

+

(

n

−

1

)

d

]

a

a

∣

∣

−−−−−−−−−−−−−−−−−−−−−−−−−

here a = 5 , d = 10-5 = 15-10 = 5 and n = 10

⇒

S

10

=

10

2

[

2

×

5

+

9

×

5

]

=

5

×

55

=

275

Answer 2

Step-by-step explanation:

15+20+dash=20+25+15

Answer=25