Răspuns :
9xla a doua +6x+1+x laa doua -6x +9 -(4x la a doua -4x+1)+x la a doua +4x +4
9xla a doua +1+x la doua +9 -4x la a doua+4x -1 + x la doua+ 4x +4=7x la doua + 13x+8
9xla a doua +1+x la doua +9 -4x la a doua+4x -1 + x la doua+ 4x +4=7x la doua + 13x+8