Răspuns:
a) 15 x 15 + 20 x 20 + 25 x 25 = 35 x 35 +5 x 5
3x5x3x5+4x5x4x5+5x5x5x5=7x5x7x5+5x5
25x9+25x16+25x25=25x49+25
25(9+16+25)=25(49+1)
25x50=25x50 Adevarat
b) 10 x 10 + 20 x 20 + 25 x 25 + 30 x 30 = 45 x 45
5x2x5x2+5x4x5x4+5x5x5x5+5x6x5x6=5x9x5x9
25x4+25x16+25x25+25x36=25x81
25(4+16+25+36)=25x81
25x81=25x81 Adevarat
c) 20 x 20 + 35 x 35 = 40 x 40 + 5 x 5
5x4x5x4+5x7x5x7=5x8x5x8+25
25x16+25x49=25x64+25
25(16+49)=25x65
25x65=25x65 Adevarat
Explicație pas cu pas: