Question

If (x-n)(nx+5)=nx^2-4x+k, what is n+k?

Answer 1

expand the left and side and then equate the coefficients

\[(x-n)(nx+5) = nx^2 +(5 - n^2)x - 5n\]

so equating coefficients on the right hand side

\[(5 - n^2) = - 4\]

and

-5n = k

add n to both sides

-4n = k + n