find the value of x^3 + y^3 + 15xy + 125, if x+y = 5
Answers
Answered by
1
(x+y) = 5
(x+y)^3 = 5^3
x^3+y^3+3xy(x+y)= 125
x^3+y^3+15xy-125 = 0
adding 250 both sides
x^3+y^3+15xy-125+250=+250
x^3+y^3+15xy+125=250
(x+y)^3 = 5^3
x^3+y^3+3xy(x+y)= 125
x^3+y^3+15xy-125 = 0
adding 250 both sides
x^3+y^3+15xy-125+250=+250
x^3+y^3+15xy+125=250
anshaj0001:
question is asking +125
@_@ leave it!
ask anyone he she will also did it
use brain
u have added 250!!
yes
i guess we have cube both the sides of x+y = 5
bez find the value x^3 + y^3 + 15xy + 125 and i find x^3+y^3+15xy-125 = 0
so tomake +125 i add it
ok....got it
Answered by
2
Hey Angel ...
--> x = y - 5 ;
--> ( x³ + y³ ) + 15xy + 125
= ( x + y )³ - 3xy( x + y ) + 15xy + 125 --->[ ( x + y )³ = x³ + y³ + 3xy( x + y )]
= ( 5 )³ - 3*5*xy + 15xy + 125
= 125 - 15xy + 15xy + 125
= 250 √√
Hence, ( x³ + y³ ) + 15xy + 125 = 250
^_^ Hope this helps ...
--> x = y - 5 ;
--> ( x³ + y³ ) + 15xy + 125
= ( x + y )³ - 3xy( x + y ) + 15xy + 125 --->[ ( x + y )³ = x³ + y³ + 3xy( x + y )]
= ( 5 )³ - 3*5*xy + 15xy + 125
= 125 - 15xy + 15xy + 125
= 250 √√
Hence, ( x³ + y³ ) + 15xy + 125 = 250
^_^ Hope this helps ...
tnx again
i got so something else...hehe
:p Told ya
i hot the answer as """""'0"""""
=_=
got°
=_= So that means -->> There must have been a minus 125 in the question
ummm
yes... galat question likh diya
anyways..leave it...i got the answer...tnx for ur help
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