Question

Q.18.The sum of the expressions x ^ 2 - 5y ^ 2 - 1, y ^ 2 - 5x ^ 2 - x ^ 2 + 5 - y ^ 2 is - 5x ^ 2 4
(B) - 5x ^ 2 - 5y ^ 2 + 4
(C) - 6x ^ 2 - 6y ^ 2
(D) 4 (A) 2x ^ 2 - 2​

Answer 1

Answer:

The correct option is (B) - 5x ^ 2 - 5y ^ 2 + 4 .

Step-by-step explanation:

x^ 2 - 5y ^ 2 - 1 + y ^ 2 - 5x ^ 2 + (- x ^ 2 + 5 - y ^ 2)

=x^ 2 - 5y ^ 2 - 1 + y ^ 2 - 5x ^ 2 - x ^ 2 + 5 - y ^ 2

= x^ 2 - 5x ^ 2 - x ^ 2 + 5y^2 + y ^ 2- y^2 +5 -1

= - 5x ^ 2 - 5y ^ 2 + 4