Advertisements
Advertisements
Question
If x + y = 9, xy = 20
find: x - y
Sum
Advertisements
Solution
x + y = 9, xy = 20
We know (a + b)
= a2 + 2ab + b2
∴ (x + y)2
= 81 x2 + y2 + 2xy
⇒ x2 + y2
= 81 - 2(120)
= 41
We also know (a - b)2
= a2 - 2ab + b2
⇒ (x - y)2
= x2 - 2xy + y2
⇒ (x - y)2
= 41 - 2(20)
= 1
⇒ x - y
= ±1.
shaalaa.com
Is there an error in this question or solution?
APPEARS IN
RELATED QUESTIONS
Factorise the following:
64m3 – 343n3
Simplify the following products:
`(x/2 - 2/5)(2/5 - x/2) - x^2 + 2x`
Simplify of the following:
(x+3)3 + (x−3)3
Find the following product:
(1 + x) (1 − x + x2)
If \[\frac{a}{b} + \frac{b}{a} = - 1\] then a3 − b3 =
If the volume of a cuboid is 3x2 − 27, then its possible dimensions are
Use the direct method to evaluate :
`(3/5"a"+1/2)(3/5"a"-1/2)`
Expand the following:
(x - 3y - 2z)2
If x + y + z = p and xy + yz + zx = q; find x2 + y2 + z2.
Using suitable identity, evaluate the following:
101 × 102
