Advertisements
Advertisements
प्रश्न
If a2 + b2 + c2 = 20 and a + b + c = 0, find ab + bc + ca.
Advertisements
उत्तर
Recall the formula
`(a+b+c)^2 = a^+b^2 +c^2 +2(ab +bc +ca)`
Given that
`a^2 +b^2 +c^2 = 20`
`(a+b+c) = 0`
Then we have
`(a+b+c)^2 = a^2 +b^2 +c^2 +2 (ab +bc + ca)`
`(0)^2 = 20 +2(ab +bc + ca)`
` 20+2(ab +bc + ca) = 0`
`2(ab + bc + ca) = -20`
`(ab +bc + ca) = -10`
APPEARS IN
संबंधित प्रश्न
Factorize (x + 2)(x2 + 25) -10x2 - 20x
Factorize `21x^2 - 2x + 1/21`
Factorize the following expressions:
1029 – 3x3
Multiply: 9x2 + 25y2 + 15xy + 12x − 20y + 16 by 3x − 5y + 4
Divide: 2a2 - 11a + 12 by a - 4
Divide: 35a3 + 3a2b - 2ab2 by 5a - b
Write in the form of an algebraic expression:
Perimeter (P) of a rectangle is two times the sum of its length (l) and its breadth (b).
Construct a formula for the following:
Total wages (₹ W) of a man whose basic wage is (₹ B) for t hours week plus (₹ R) per hour, if he Works a total of T hours.
Complete the table.
| × | 2x2 | −2xy | x4y3 | 2xyz | (___)xz2 |
| x4 | |||||
| (___) | 4x5y4 | ||||
| −x2y | |||||
| 2y2z | −10xy2z3 | ||||
| −3xyz | |||||
| (___) | −14xyz2 |
If x = 2 and y = 3, then find the value of the following expressions
4y – x
