History of Hindu Mathematics: A Source Book v2.c17.s23.8

v2.c17.s23.8

Similarly, for the solution of (*ii*), he assumes $x² = 5z² + 1, y² = 4z²,$ which satisfy the equations. By the method of the Square-nature the values of (z, x) in the equation 5z² + 1 = x² are (4, 9), (72, 161), etc. Hence the solutions of (*ii*) are $.x &= 9 / y &= 8, .x &= 161 / y &= 144,$