Question

solve the simulataneous equations x^2+y^2=21 y=2x-3

Answer 1

$x {}^{2} + (2x - 3) {}^{2} = 21 \\x {}^{2} + 4x {}^{2} - 9 = 21 \\ 5x {}^{2} = 30 \\ x {}^{2} = \frac{30 }{5 } \\ x {}^{2} = 6 \\ x = \sqrt{6}$