Q9 of 114 Page 3

Observe the following pattern



And find the values of each of the following:


(i) 1+2+3+4+5+……….+50


(ii) 31+32+……..+50

R.H.S = [No. of terms in L.H.S × (No. of terms + 1)] (Therefore, only when L.H.S starts with 1)

Therefore,

(i) 1 + 2 + 3 +…..50 = [50 × (50 + 1)]

= 25 × 51

= 1275

(ii) 31 + 32 +…..+50 = (1 + 2 + 3 + …. + 50) – (1 + 2 + ….. 30)

= 1275 – [ (30 × 30 +1)]

= 1275 – 465

= 810

More from this chapter

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7

Which of the following triplets are Pythagorean?

(i) (8, 15, 17)


(ii) (18, 80, 82)


(iii) (14, 48, 51)


(iv) (10, 24, 26)


(v) (16, 63, 65)


(vi) (12, 35, 38)

 8

Observe the following pattern


And find the value of


 10

Observe the following pattern


And find the values of each of the following.


(i)


(ii)

11

Which of the following numbers are squares of even numbers?

121, 225, 256, 324, 1296, 6561, 5476, 4489, 373758