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 the following expressions:
y3 +125
Factorize the following expressions:
(a + b)3 – 8(a – b)3
Simplify `(155 xx 155 xx 155 - 55 xx 55 xx 55)/(155 xx 155 + 155 xx 55 + 55 xx 55)`
Factorize a3 – 3a2b + 3ab2 – b3 + 8
`1/27 x^3 - y^3 + 125z^3 + 5xyz`
Write the number of the term of the following polynomial.
23 + a x b ÷ 2
Express the following as an algebraic expression:
Sum of p and 2r – s minus sum of a and 3n + 4x.
Write the coefficient of x2 and x in the following polynomials
`4 + 2/5x^2 - 3x`
Complete the table.
| × | 2x2 | −2xy | x4y3 | 2xyz | (___)xz2 |
| x4 | |||||
| (___) | 4x5y4 | ||||
| −x2y | |||||
| 2y2z | −10xy2z3 | ||||
| −3xyz | |||||
| (___) | −14xyz2 |
Express the following properties with variables x, y and z.
Associative property of multiplication
