Помогите решить (m-n+1)(m+n) 8x-(3x+1)(6x+1)

(m-n+1)(m+n)=m²+mn-mn-n²+m+n=m²-n²+m+n8x-(3x+1)(6x+1)=8x-(18x²+3x+6x+1)=8x-18x²-3x-6x-1=-18x²-x-1

(m-n+1)(m+n)=m^2+mn-mn-n^2+m+n=m^2-n^2+m+n

8x-(3x+1)(6x+1)=8x-(18x^2+3x+6x+1)=8x-(18x^2+9x+1)=8x-18x^2-9x-1=-18x^2-x-1