X ^ 2 - 21 = 4x July 8, 2019 16 32 64 128 X 2 21 4x X 2 4x 21 0 X 2 4x 21 factored X 2 4x 21 0 solve by factoring X 2 4x 21 0 complete the square X 2 4x 21 0 factoring X 2 4x 21 =- 9 X 2 4x 21 0 дискриминант X 2 4x 21 0 discriminant Х 2 4x 21 0 Y x 2 4x 21 X 3 x2 4x 21 Fully factorise x 2 4x 21 X 4 4x 2 21 0 − x 2 − 4x 21 ≥ 0
