If x
3
=184+y
3
and x=4+y, then the value of (x+y) is (given that x>0 and y>0):
- A−2
11
- B2
14
- C−2
14
- D2
11
Solution & Step-by-step Explanation
Given equations:
x
3
−y
3
=184
x−y=4
We know the algebraic identity:
x
3
−y
3
=(x−y)(x
2
+xy+y
2
)
184=4(x
2
+xy+y
2
)
x
2
+xy+y
2
=46
We can express x
2
+xy+y
2
as:
x
2
+xy+y
2
=(x−y)
2
+3xy
46=(4)
2
+3xy
46=16+3xy
3xy=30⟹xy=10
Now we need to find the value of (x+y). We use the identity:
(x+y)
2
=(x−y)
2
+4xy
(x+y)
2
=4
2
+4(10)
(x+y)
2
=16+40=56
x+y=±
56
=±2
14
Since it is given that x>0 and y>0, their sum (x+y) must be positive.
x+y=2
14
x
3
−y
3
=184
x−y=4
We know the algebraic identity:
x
3
−y
3
=(x−y)(x
2
+xy+y
2
)
184=4(x
2
+xy+y
2
)
x
2
+xy+y
2
=46
We can express x
2
+xy+y
2
as:
x
2
+xy+y
2
=(x−y)
2
+3xy
46=(4)
2
+3xy
46=16+3xy
3xy=30⟹xy=10
Now we need to find the value of (x+y). We use the identity:
(x+y)
2
=(x−y)
2
+4xy
(x+y)
2
=4
2
+4(10)
(x+y)
2
=16+40=56
x+y=±
56
=±2
14
Since it is given that x>0 and y>0, their sum (x+y) must be positive.
x+y=2
14