(3X-5)(3X-5)+(3X+5)(3X+5)

(-15)(-15)+(15)(15)
=-30+30
=0

=(9×2 – 15x -15x + 15) +(9×2 + 15x + 15x + 15)
=9×2 -30x +15 + 9×2 + 30x + 15
= 18×2 + 30