Advertisements
Advertisements
प्रश्न
If 9x2 + 25y2 = 181 and xy = −6, find the value of 3x + 5y
Advertisements
उत्तर
We have,
`(3x + 5y)^2 = (3x)^2 + (5y)^2 + 2 xx 3x xx 5y`
`=> (3x + 5y)^2 = 9x^2 + 25y^2 + 30xy`
`= 181 + 30(-6)` [∵ `9x^2 + 25y^2 = 181` and xy = -6]
= 181 - 180
`=> (3x + 5y)^2 = 1`
`=> (3x + 5y)^2 = (-+1)^2`
`=> 3x + 5y = +-1`
APPEARS IN
संबंधित प्रश्न
Factorise the following using appropriate identity:
4y2 – 4y + 1
Write the following cube in expanded form:
(2a – 3b)3
Evaluate following using identities:
991 ☓ 1009
Simplify the following products:
`(m + n/7)^3 (m - n/7)`
If a − b = 4 and ab = 21, find the value of a3 −b3
If \[x - \frac{1}{x} = 7\], find the value of \[x^3 - \frac{1}{x^3}\].
Evaluate of the following:
(9.9)3
Find the value of 27x3 + 8y3, if 3x + 2y = 20 and xy = \[\frac{14}{9}\]
Find the following product:
(2ab − 3b − 2c) (4a2 + 9b2 +4c2 + 6 ab − 6 bc + 4ca)
Evaluate:
483 − 303 − 183
If \[x + \frac{1}{x} = 3\] then \[x^6 + \frac{1}{x^6}\] =
Use identities to evaluate : (998)2
Use the direct method to evaluate the following products :
(y + 5)(y – 3)
Use the direct method to evaluate :
(x+1) (x−1)
Evaluate: (2 − z) (15 − z)
Evaluate: `(2"x"-3/5)(2"x"+3/5)`
Evaluate: 20.8 × 19.2
If `"a" - 1/"a" = 10;` find `"a" + 1/"a"`
If `x + (1)/x = 3`; find `x^4 + (1)/x^4`
If x + y + z = p and xy + yz + zx = q; find x2 + y2 + z2.
