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:
8a3 – b3 – 12a2b + 6ab2
If 3x − 2y = 11 and xy = 12, find the value of 27x3 − 8y3
Evaluate of the following:
(99)3
Evaluate of the following:
463+343
If \[\frac{a}{b} + \frac{b}{a} = - 1\] then a3 − b3 =
If a − b = −8 and ab = −12, then a3 − b3 =
Evalute : `( 7/8x + 4/5y)^2`
Evaluate `(a/[2b] + [2b]/a )^2 - ( a/[2b] - [2b]/a)^2 - 4`.
If a - b = 4 and a + b = 6; find
(i) a2 + b2
(ii) ab
The number x is 2 more than the number y. If the sum of the squares of x and y is 34, then find the product of x and y.
Use the direct method to evaluate :
(2+a) (2−a)
Use the direct method to evaluate :
(2a+3) (2a−3)
Expand the following:
(2p - 3q)2
Find the squares of the following:
(2a + 3b - 4c)
Simplify by using formula :
`("a" + 2/"a" - 1) ("a" - 2/"a" - 1)`
If `"a" + 1/"a" = 6;`find `"a" - 1/"a"`
Simplify:
(7a +5b)2 - (7a - 5b)2
Simplify:
(2x + y)(4x2 - 2xy + y2)
Find the value of x3 + y3 – 12xy + 64, when x + y = – 4
