Question

7.1 + 3+ 5 + 7 + ... + 49 should be equal to (a) 492 (b) 24 (c) 252 (d) None of these 8. 10.9 x V1.6 = ? (a) 0.12 (b) 1.2 (c) 0.75 (d) 12

11th - 12th Class

Maths

Solution

234

4.0 (1 ratings)

1+ ( 3+5+7+--+49 ) ( a_{n}=49 ) ( a=1 ) ( a=2 ) ( a_{n}=a+(n-1) d ) ( 49=1+(n-1) times 2 ) ( n-1=frac{48}{2} ) ( n=27+1=25 ) ( 5 n=frac{25}{2} times(1+49) ) ( =frac{25}{2} times 50=25 times 25=(25)^{2} )