(87³+72³)/159 - 87*82 =
= (87+82)(87²-87*72+72²) /159 -87*82 =
=159(87²-87*72+72^2) / 159 - 87*82 =
=87² – 87*82 +72^2 -87*82 =
=87² -2*87*82+72²=( 87 -72)²=15²=225
*formuła: (a³+b³ ) i ( a-b)²
