r=23⋅5x+7⇒r2=(23⋅5x+7)2=(23⋅5)2(x+7)2=(23)2(5)2(x+7)(x+7)
=(20+3)2(25)x⋅x+7x+7x+7(7)
=((20)(20)+(3)(20)+(3)(20)+(3)(3))(25)x2+14x+49
=(400+60+60+9)(25)x2+14x+49
=(400+120+9)(25)x2+14x+49=(529)(25)x2+14x+49
=(529)(20+5)x2+14x+49=529(20)+529(5)x2+14x+49
=2(5290)+5290(12)x2+14x+49=10580+2645x2+14x+49
13225x2+14x+49