Question 22374
9x^2+24xy-9y^2 ..WE FIND 3 IS A COMMON FACTOR AND TAKE IT OUT..
=3(3X^2+8XY-3Y^2)
TAKE PRODUCT OF COEFFICIENTS OF X^2 AND Y^2 TERMS .THEY ARE 3 AND -3 .SO PRODUCT = 3*-3=-9
NOW TRY BY GUESS 2 FACTORS OF THIS PRODUCT -9 WHOSE SUM IS THE COEFFICIENT OF XY TERM THAT IS 8..WE TRY..
-9=-1*9....SUM IS -1+9=8..OK.. HENCE 8 XY = -1XY+9XY ...SO NOW WE WRITE 
=3(3X^2-1XY+9XY-3Y^2)
3{X(3X-Y)-3Y(3X-Y)}=3(X-3Y)(3X-Y)