SOLUTION: please help me to solve this problem prove it roots of of this equation ; ( x^2+(mx+c)^2=a^2) will be equal if (c^2=a^2(1+m^2))

Algebra ->  Square-cubic-other-roots -> SOLUTION: please help me to solve this problem prove it roots of of this equation ; ( x^2+(mx+c)^2=a^2) will be equal if (c^2=a^2(1+m^2))      Log On


   



Question 773968: please help me to solve this problem
prove it
roots of of this equation ; ( x^2+(mx+c)^2=a^2) will be equal if (c^2=a^2(1+m^2))

Answer by ramkikk66(644) About Me  (Show Source):
You can put this solution on YOUR website!
roots of of this equation ; ( x^2+(mx+c)^2=a^2) will be equal if (c^2=a^2(1+m^2))

Expanding the given equation
x%5E2+%2B+m%5E2%2Ax%5E2+%2B+2%2Am%2Ac%2Ax+%2B+c%5E2+-+a%5E2+=+0

Rewriting it in standard quadratic form

%28m%5E2+%2B+1%29x%5E2+%2B+2%2Am%2Ac%2Ax+%2B+c%5E2+-+a%5E2+=+0
This is of the form A*x^2 + B*x + C = 0 (I am writing A, B, C in uppercase so 
that you don't confuse them with the a,b,c given in the problem)

The roots of the quadratic are equal if the "discriminant" is 0

Discriminant = %28B%5E2+-+4%2AA%2AC%29 -----> (1)

Here A = (1 + m^2) ---> coefficient of x^2 term
B = 2*m*c  -----> coefficient of x term
C = c^2 - a^2 -----> constant term

Discriminant(substituting for A,B,C in eqn (1))
%282%2Am%2Ac%29%5E2+-+4%2A%281+%2B+m%5E2%29%2A%28c%5E2+-+a%5E2%29
= 4%2Am%5E2%2Ac%5E2+-+4%2A%281+%2B+m%5E2%29%2A%28c%5E2+-+a%5E2%29+=+0
cross%28m%5E2%2Ac%5E2%29+-c%5E2+%2B+a%5E2+-+cross%28m%5E2%2Ac%5E2%29+%2B+a%5E2%2Am%5E2+=+0
-c%5E2+%2B+a%5E2+%2B+a%5E2%2Am%5E2+=+0
c%5E2+=+a%5E2+%2B+a%5E2%2Am%5E2+=+a%5E2%2A%281+%2B+m%5E2%29 -> proved!

Hope you got it :)