# Numbers and Algebra - Numbers and Algebra Section 1

>>>>>>>>>>Numbers and Algebra Section 1

• A

0  • B

1  • C

2  • D

3  • Option : D
• Explanation : x2/yx + y2/zx + z2/xy
...(since, x+y+z=0  x3+y3+z3=3xyz)
(x3+y3+z3) / xyz = 3xyz / xyz = 3.

• A

32 years  • B

35 years  • C

33 years  • D

34 years  • Option : B
• Explanation : Increase after 5 years should have been 7 x 5 = 35 years. But since average remains same, diference in their age is 35 years.

• A

32  • B

53  • C

46  • D

39  • Option : D
• Explanation : L.C.M. of 9, 10 and 15 = 90 ∴ 1936 = 90 x 21 + 46 (Remainder). But a part of this remainder is 7. 39 should be subtracted from 1936.

• A

840  • B

880  • C

930  • D

1120  • Option : C
• Explanation :

Since d = -2, maximum sum of the series will be sum of all the positive terms.
Least positive term of the series is 2 or 0 (both giving equal sum)
Let, 2 be the nth term
2 = 60 + (n 1) - 2
=> n = 30
Required sum = 30/2 (60 + 2) = 930

• A

210  • B

414  • C

420  • D

426  • Option : D
• Explanation :

L.C.M. of 12, 21 and 35 = 420
∴ Number required = 420 + 6 = 426