Basic question at algebra

Algebra Level 1

x+y = 3

xy = 2

find x 5 + y 5 x^5+y^5


The answer is 33.

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5 solutions

x + y = 3 x = 3 y x+y=3\rightarrow\;x=3-y Replacing this value in the second equation,we get: ( 3 y ) ( y ) = 2 (3-y)(y)=2 3 y y 2 = 2 3y-y^2=2 y 2 3 y = 2 y^2-3y=2 y 2 3 y 2 = 0 y^2-3y-2=0 ( y 2 ) ( y 1 ) = 0 y = 2 o r y = 1 (y-2)(y-1)=0\rightarrow\;y=2\;or\;y=1 If we put the possible values of y y in x + y = 3 x+y=3 we get x = 1 o r x = 2 x=1\;or\;x=2 It is obvious that x 5 + y 5 x^5+y^5 will give the same answer irrespective if the values of x , y x,y So x 5 + y 5 = 1 5 + 2 5 = 2 5 + 1 5 = 33 x^5+y^5=1^5+2^5=2^5+1^5=\boxed{33}

Sorry. y 2 3 y = 2 y^2-3y=-2 and the next equation is y 2 3 y + 2 = 0 y^2-3y+2=0

Abdur Rehman Zahid - 6 years, 7 months ago
Taru Bhardwaj
Nov 14, 2014

please pay attention x+y=3 xy=2 x=2 or 1 and y=1 or 2 assuming x to be 2 and y to be 1 x to power 5=32 and y to power 5=1 therefore the answer is 33

Rahul Chandani
Nov 14, 2014

The equation which will have roots x and y is a^2 - 3a + 2 = 0

therefore x and y will gain values 2 and 1.

2^5 + 1^5 = 33

Galen Buhain
Feb 27, 2016

Let x =1 and y=2. x+y=3 . xy=2. x= 1 and y= 32 the answer is 33

Frankie Fook
Feb 28, 2015

x+y=3,thus consider x and y are two integers,3/2=1.5 means that 1<1.5<2 mean 1~1.5~2,x and y possibly be 2 or 1, just consider that x as 2 then and y as 1 so x^5+y^5=2^5+1^5=32+1=33

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