Question Details

Which one among the following is correct if x, y, z are eliminated from, (bx/y+z = a, cy/z+x = b, az/x+y = c)?

Options

A

a²b + b²c + c²a + abc = 0

B

a²b – b²c + c²a + abc = 0

C

a²b + b²c + c²a + 2abc = 0

D

a²b – b²c – c²a – abc = 0

Correct Answer :

a²b + b²c + c²a + abc = 0

Solution :

We are given the following set of equations:

bxy+z = a (Equation 1)

cyz+x = b (Equation 2)

azx+y = c (Equation 3)

Let us rewrite these equations in terms of ratios of the variables x, y, and z.
From Equation 1, we can write:
bx=a(y+z) xy+z=ab
Adding 1 to both sides (componendo):
xy+z+1=ab+1 x+y+zy+z=a+bb
Taking the reciprocal:
y+zx+y+z=ba+b (Equation 4)

Similarly, using Equation 2, we have:
cy=b(z+x) yz+x=bc
Adding 1 to both sides:
x+y+zz+x=b+cc
Taking the reciprocal:
z+xx+y+z=cb+c (Equation 5)

Similarly, using Equation 3, we have:
az=c(x+y) zx+y=ca
Adding 1 to both sides:
x+y+zx+y=c+aa
Taking the reciprocal:
x+yx+y+z=ac+a (Equation 6)

Now, let us add Equation 4, Equation 5, and Equation 6:
y+zx+y+z + z+xx+y+z + x+yx+y+z = ba+b + cb+c + ac+a
Simplifying the left-hand side:
2(x+y+z)x+y+z = ba+b + cb+c + ac+a
2 = ba+b + cb+c + ac+a

Subtracting 1 from both sides of the Equation:
1 = ba+b-1 + cb+c + ac+a
1 = -aa+b + cb+c + ac+a
Let us rearrange the terms to simplify calculations:
1 - cb+c = ac+a - aa+b
bb+c = a1c+a-1a+b
bb+c = a(a+b)-(c+a)(c+a)(a+b)
bb+c = a(b-c)(c+a)(a+b)

Cross-multiplying the terms:
b(c+a)(a+b) = a(b-c)(b+c)
b(ac+bc+a2+ab)= a(b2-c2)
abc+b2c+a2b+ab2 = ab2-ac2

Subtracting ab2 from both sides, we get:
a2b+b2c+abc = -c2a
Rearranging all the terms to one side:
a2b+b2c+c2a+abc=0

This matches the relationship in the correct answer.

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