Status: Waiting for your answers. Using the partially completed work below, solve the equation x^{2} + 10x + 21 = 0 by completing the square. x^{2} + 10x + 21 = 0Step 1:x^{2} + 10x = Step 2: x^{2} + 10x + = Step 3: (x + )^{2} = Step 4: x + = + Step 5: x = + Step 6: x_{1}x_{2} = = - = -7 + = -3