Question

please solve this question​

Answer 1

Step-by-step explanation:

I think that is correct answer

Answer 2

Answer:

k= 1/4

Step-by-step explanation:

81y^2-k=9y+1/2×9y-1/2

81y^2-k=81^2-1/4(a+b)(a-b)=a^2-b^2

-k=81y^2-81y^2-1/4

-k=-1/4

k=1/4