if x+y = 5 and xy=6 .find x^3+y^3
plzzz answer this i hv exam tomorrow ;(((
Answers
Answered by
1
Heya buddy !!!
Here's the answer you are looking for
x³ + y³ = (x + y)(x² + y² - xy)
We have, x + y = 5
Squaring both sides we get,
(x + y)² = 5²
x² + y² + 2xy = 25
x² + y² = 25 - 2xy = 25 - 2(6) = 25 - 12
So, x² + y² = 13
Now we got all the unknown values and can put these values in the x³ + y³
So, x³ + y³ = 5 ( 13 - 6) = 5(7) = 35
Therefore, the value of x³ + y³ is 35
ALTERNATIVE WAY
(x + y)³ = x³ + y³ + 3(x+y)(xy)
5³ = x³ + y³ + 3(5)(6)
125 = x³ + y³ + 90
So, x³ + y³ = 125 - 90 = 35.
Therefore, the value of x³ + y³ is 35
★★ HOPE THAT HELPS ☺️ ★★
Here's the answer you are looking for
x³ + y³ = (x + y)(x² + y² - xy)
We have, x + y = 5
Squaring both sides we get,
(x + y)² = 5²
x² + y² + 2xy = 25
x² + y² = 25 - 2xy = 25 - 2(6) = 25 - 12
So, x² + y² = 13
Now we got all the unknown values and can put these values in the x³ + y³
So, x³ + y³ = 5 ( 13 - 6) = 5(7) = 35
Therefore, the value of x³ + y³ is 35
ALTERNATIVE WAY
(x + y)³ = x³ + y³ + 3(x+y)(xy)
5³ = x³ + y³ + 3(5)(6)
125 = x³ + y³ + 90
So, x³ + y³ = 125 - 90 = 35.
Therefore, the value of x³ + y³ is 35
★★ HOPE THAT HELPS ☺️ ★★
Nightmare1069:
which is correct ??
im sure about my answer....
In the other answer he wrote x³ + y³ = (x+y)³ which is wrong
but my teacher told me to do x^3+y^3+ 3xy(x+y)
plzz solve in this way
not sure if he would give marks
done......check the answer
but u took square
its cube
what?? where i took square??
Answered by
0
x^3 + y^3 =(x+y) (x^2+2xy+y^2)
(5)^3=(5) (x^2+12+y^2)
125/5-12=(x^2+y^2)
25-12=(x^2+y^2)
13 = x^2+y^2
(5)^3=(5) (x^2+12+y^2)
125/5-12=(x^2+y^2)
25-12=(x^2+y^2)
13 = x^2+y^2
which is correvt
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