History of Hindu Mathematics: A Source Book v2.c17.s25.84

v2.c17.s25.84

(*i*) Set x=w²-1, y=2w; then we find that x-y+2=(w-1)², x+y+2=(w+1)², x² - y² + 8 &= (w² - 3)², \\ x² + y² &= (w² + 1)², \\ 1/2(xy + y) &= w³. \end{aligned}