| Question 136. I request for Social science Mock test. When can we get it because only few days are left for board exams ? by Sumati. Answered on March 1, 2008 at 1:30pm I.S.T. | Answer 136.We have already added CBSE Social Science Mock test (full syllabus paper) yesterday. This is in addition to CBSE Mathematics Mock test. click here |
| Question 137.What a zero of a polynomial ? by Nain Agarwal. Answered on March 4, 2008 at 10:55pm I.S.T. | Answer 137.. A real number c is said to be zero of a polynomial p(x) if p(c) = 0 |
| Question 138. Prove converse of mid point theorem by basic proportionality theorem? by Nikhil Sharma. Answered on March 05 2008 at 5:19 pm I.S.T. | Answer 138. P and Q are points on sides AB and AC respectively of triangle ABC such that AP = PB and PQ II BC. By basic proportionality theorem AP/PB = AQ/QC AP/AP = AQ/QC [since AP = PB] 1 = AQ/QC AQ = QC Statement of converse of Mid Point Theorem - A line from midpoint of one side of a triangle, parallel to second side bisects the third side. |
| Question 139. Define an irrational number by Ruchi Sharma. Answered on March 6, 2008 at 7:45 pm I.S.T. | Answer 139. A real number is irrational if it cannot be represented in p/q form, where p and q are integers and q is not equal to zero |
| Question 140. I am a class viii student going to class iX. By when will we get new sample papers for class ix by Aashish. Answered on March 9, 2008 at 11:15 pm | Answer 140. new sample papers of class ix chapterwise will be available beginning end of march. After chapterwise tests we will add bigger papers. |
| Question 141. If a-b = b-c and y^2 = xz, prove that x ^(b-c) × y ^(c-a) × z ^(a-b) = 1 by Diptesh Answered on March 10, 2008 at 7:37 pm I.S.T. | Answer 141. a-b = b-c or 2b = a + c or 2b - 2a = a + c - 2a or 2(b - a) = c - a Let a-b = b-c = k Therefore c - a = 2(b - a) = - 2k L.H.S. = x ^(b-c) × y ^(c-a) × z ^(a-b) = x ^k × y ^(-2k) × z ^k = x ^(k - 2k + k) = x^0 = 1 = R.H.S. |
| Question 142. Solve for x, (x+1)(x+2)(x+3)(x+4) = 120 by Nivetha. Answered on March 13, 2008 at 7:14pm | Answer 142. (x+1)(x+2)(x+3)(x+4) = 120 or (x+1)(x+4)(x+3)(x+2) = 120 or (x^2 + 5x + 4) (x^2 + 5x + 6) = 120 or (y + 4)(y + 6) = 120 or y^2 + 10y + 24 = 120 or y^2 + 10y - 96 = 0 or (y + 16) (y - 6) = 0 or ( x^2 + 5x + 16) ( x^2 + 5x - 6) = 0 x^2 + 5x + 16= 0, no real values x^2 + 5x - 6 = 0 (x + 6)(x - 1) = 0 x = - 6, x = 1 |
| Question 143. Is 1 a prime number ? by Tejas. Answered on March 15, 2008 at 7:47 pm | Answer 143. 1 is not a prime number. It has only one factor whereas prime numbers have exactly 2 factors. |
| Question 144. If tan A + 1/ tan A = 2 Find the value of (tan^2)A +1/ (tan^2)A by Sumanthathreya. Answered on March 20 at 8:30 P.M | Answer 144. If tan A + 1/ tan A = 2 Squaring both sides (tan^2)A +1/ (tan^2)A + 2 = 4 (tan^2)A +1/ (tan^2)A = 4 - 2 (tan^2)A +1/ (tan^2)A = 2 |
| Question 145. Is 18×25×25 + 25 a composite no? why? by Babli. Answered on March 23, 2008 at 10:08 a.m. | Answer 145. 18×25×25 + 25 = 25(450 + 1) = 25 × 451 which is composite since it has 2 factors other than one. |
| Question 146. Are maths and Science books of class V111 available online anywhere? by Randhir Singh. Answered on March 26, 2008 at 12:01 p.m. | Answer 146. These books are available here |
| Question 147. How many polynomials having zeros 10 and - 10 can be written? by Abhishek. Answered on March 31, 2008 at 9:18 p.m. | Answer 147.Infinitely many. k(x - 10)(x + 10) where k is any real number. |
| Question 148. find the cube root of 531441 using prime factorisation method by M.V. Nivya. Answered on April 4, 2008 at 11:23 p.m. | Answer 148. 531441 = 3^12 cube root of 531441 = ( 3^12)^1/3 = 3^4 = 81 |
| Question 149. Use Euclid’s division algorithm to find the HCF of (i) 135 and 225 (ii) 196 and 38220 (iii) 867 and 255 by Aman Kumar. Answered on April 06, 2008 at 1:52 p.m. | Answer 149. I will answer one of these. 196 and 38220 Since 38220 > 196 we apply Euclid's division lemma to 38220 and 196 38220 = 196 × 195 + 0 Since remainder = 0, so we stop. The divisor here is 196 so HCF of given numbers = 196 |
| Question 150. How to write 3x^2 + 5 - 6x in standard form in two ways? by Priya. Answered April 14, 2008 at 8:56 p.m. | Answer 150. 3x^2 - 6x + 5 and 5 - 6x + 3x^2 |