| Question 151. The 20th term of AP exceeds its 15th term by 10. find the common difference. by Yasmeenshastha. Answered on April 16, 2008 at 7:41 p.m. |
| Answer 151. T20 - T15 = 10 a + 19d - (a + 14d) = 10 5d = 10 d = 2 |
| Question 152. Find the least no. That must be subtracted from 893304 so as to get perfect square by Himanshu Srivastava. Answered on April 19, 2008 at 10:37 p.m. |
| Answer 152. 9 ) 893304 ( 945 81 ----------------- 184 ) 833 ( 736 ------------------ 1885) 9704 ( 9425 ------------------ 279 No. to subtracted from 893304 to get perfect square = 279 |
| Question 153. When will we get papers of VI and VIII by Anusuya. Answered on April 23, 2008 at 7:34 p.m. |
| Answer 153. We plan to add sample papers of Mathematics class VIII by June 2008. |
| Question 154. Write general form of a quadratic polynomial by Shubash. Answered on April 26, 2008 at 8:08 p.m. |
| Answer 154. ax^2 + bx + c where a, b and c are real numbers and a is not equal to zero. |
| Question 155. Every integer is a rational number. Is this statement true. Why? By Harinder. Answered on May 01, 2008 at 8:15 p.m. |
| Answer 155. True because each integer can be written with denominator 1 which brings it in the form of p/q where p and q are integers and q is not zero. |
| Question 156. Three consecutive integers as such that when they are taken in
increasing order and multiplied by 2, 3 & 4 respectively, they add
up to 74. Find these numbers by Raya Mandal. Answered on May 02, 2008 at 9:42 p.m. |
| Answer 156. Let the three numbers be x, x + 1 and x + 2 according to problem 2x + 3(x + 1) + 4(x + 2) = 74 2x + 3x + 3 + 4x + 8 = 74 9x = 74 - 11 x = 63/9 x = 7 Therefore the numbers are 7, 8 and 9 |
| Question 157. Factorise: a^3-2a^2b+3ab^2-6b^3 by Ashwin Kumar. Answered on May 08, 2008 at 8:12 p.m. |
| Answer 157. a^3-2a^2b+3ab^2-6b^3 = a^2( a - 2b) + 3b^2 (a - 2b) = ( a - 2b)(a^2 + 3b^2) |
| Question 158. What is a composite no. & how we can find out a no: is composite or not. Please explain with examples by Sidharth. Answered on May 10, 2008 at 8:09 p.m. |
| Answer 158. A number which has more than 2 factors is called a composite number. We find one factor other than 1 and the number itself which makes the number of factors more than two. There is no need to find all the factors. Eg. 12 has 2 as factor other than 1 and 12. Therefore it is a composite no. |
| Question 159. When are CBSE results 2008 class x expected? by Anubhavi . Answered on May11, 2008 at 10:04 P.M. |
| Answer 159. If we consider the result dates of 2006 and 2007 the result expected around 28 May 2008 |
| Question 160. What is the possible date for CBSE results 2008 class xii ?by Harshita. Answered on May13, 2008 at 6:42 |
| Answer 160. Taking into account the result dates of 2006 and 2007 the results xii expected around 23 May 2008 |
| Question 161. Please explain why 7x11x13+13 and 7x6x5x4x3x2x1+5 are composite numbers? I tried to explain in the following way . 7x11x13+13 =13{7x11+1} =13x78 and 7x6x5x4x3x2x1+5 =5{7x6x4x3x2x1 =5x1009 now i don't know how to conclude. Please help me, by Sidharth. Answered on May 18, 2008 at 12:41 p.m. |
| Answer 161. A composite number has more than two factors or in other words two factors other than 1. Now in question 1 you got 13x78 in second last step. Since it has two factors other than one, it is a composite no. Similarly for second. |
| Question 162. Two poles 'a' and 'b' are 'p' metres apart. Prove that the height of the
point of intersection of the lines joining the top of each pole to the
foot of the opposite pole is given by - ab/a+b metres by Namrata. Answered on May 23, 2008 at 5:29 p.m. |
| Answer 162. Let first pole 'a' be represented by AB and 'b' by CD and let they intersect at E, EF is perpendicular to BD. Now BD = 'p'. Let BF = x and FD = p - x. Also let EF = 'c' Triangle BFE ~ BDC by AA . Therefore c/b = x/p ......(i) Similarly c/a = (p-x)/p ......(ii) Adding i and ii c/b + c/a = x/p + (p-x)/p or c(a+b)/ab = (x + p - x)/p taking LCM on both sides or c(a+b)/ab = p/p or c(a+b)/ab = 1 or (a+b)/ab = 1/c or ab/(a+b) = c |
| Question 163. There is a circular path around a sports field.sonia takes 18min to drive one around of the field,while ravi takes 12min for the same.suppose they both start at the same point at the same time,and go in the same direction.after how minutes will they meet again at the starting point? by Uthra from Chennai. Answered on May 24, 2008 at 5:37 p.m. |
| Answer 163. Required time = LCM of 18 and 12 36 minutes. |
| Question 164. In triangle ABC, D and E are points on AB and AC such that DE || BC. if AD = 4x-3, AE = 8x-7, BD = 3x-1 and CE = 5x-3, find the value of x by Namrata. Answered on June 9, 2008 at 10:53 p.m. |
| Answer 164. In triangle ABC, D and E are points on AB and AC such that DE || BC Therefore AD/DB = AE/EC (4x-3)/(3x-1) = (8x-7)/(5x-3) or 20x^2 - 12x - 15x + 9 = 24x^2 - 8x - 21x + 7 or 4x^2 - 2x - 2 = 0 (÷2) or 2x^2 - x - 1 = 0 or (x - 1)(2x + 1) = 0 or x = 1, x = -1/2 (rejected) Therefore x = 1 |
| Question 165. A peacock is sitting on a tree nine metres high. A snake at a distance
of twenty Seven metres from pillar is coming to a pole at the base of
the pillar. Seeing the Snake the peacock pounces upon it. If their
speeds are equal find the distance from the hole at which the snake
caught, by Brijesh kumar. Answered on June 16, 2008 at 7:17 p.m. |
| Answer 165. This question has already been answered. See question 41 on page 3 of question answers. Click Here |