point of Intersection

(1) The sum of X-coordinate of the point of Intersection of the curves
x^{2}=x+y+4 and y^{2}=y-15x+36 in X-Y plane.

4 Answers

19
Debotosh.. ·

ans =1

1708
man111 singh ·

No
ans = 0

1
Nikhil Kaushik ·

eliminate y from (1) & substitute in (2)

u vl get an eqn in 4th degree....

now sum of roots is = -(coeff of x3)/(coeff of x4)

106
Asish Mahapatra ·

from (i) y = x2-x-4
putting this in (ii)

x4 + x2 + 16 - 2x3 + 8x - 8x2 = x2-x-4 - 15x + 36

=> x4 - 2x3 - 8x2 + 24x - 16 = 0

we need to find the sum of REAL roots (there maybe imaginary roots as well)

the above exp is factorised as

(x-2)2(x2+2x-4) = 0 (both sides give real roots)

So the sum of roots is 2 (from (x-2)2) + (-2) (from(x2+2x-4)

so the sum of roots is zero

so the sum of x-coordinates of pts of interseciton is zero.

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