Find all real solutions of x4−13x2+36=0x^4 - 13x^2 + 36 = 0x4−13x2+36=0.Ax=±2,±3x = \pm 2, \pm 3x=±2,±3check_circleBx=2,3x = 2, 3x=2,3Cx=±2,±9x = \pm 2, \pm 9x=±2,±9Dx=4,9x = 4, 9x=4,9ExplanationLet u=x2u = x^2u=x2: u2−13u+36=(u−4)(u−9)=0u^2 - 13u + 36 = (u - 4)(u - 9) = 0u2−13u+36=(u−4)(u−9)=0, so x2=4x^2 = 4x2=4 or 999, giving x=±2,±3x = \pm 2, \pm 3x=±2,±3.