Question 112424
X(X+1)=9(X+X+1)-9
X^2+X=9(2X+1)-9
X^2+X=18X+9-9
X^2+X-18X=0
X^2-17X=0
X(X-17)=0
X=0 ANSWER.
X-17=0
X=17 ANSWER.
PROOF.
17*18=9(17+18)-9
306=9*35-9
306=315-9
306=306