Question

if a²+b²+c²= 2(3a-4b-6c)-61, then the value lof a-b-c is​

Answer 1

a^2 + 9 - 6a - b^2 + 16 + 18b + c^2 + 36 + 12c = 0

= (a-3)^2 + (b+4) + (c+6)^2 = 0

= here, a = 3 , b = - 4 , c = - 6

(a- b-c) = (3+4+6) = 13