Question

x^4 -4*(x^2+5)-25 giải dùm ạ

Answer 1

\(x^4-4\left(x^2+5\right)-25\\ =x^4-25-4\left(x^2+5\right)\\ =\left(x^2+5\right)\left(x^2-5\right)-4\left(x^2+5\right)\\ =\left(x^2+5\right)\left(x^2-5-4\right)\\ =\left(x^2+5\right)\left(x^2-9\right)\\ =\left(x^2+5\right)\left(x+3\right)\left(x-3\right)\)

Answer 2

x⁴ - 4(x² + 5) - 25

= x⁴ - 4x² - 20 - 25

= x⁴ - 4x² - 45

= x⁴ - 9x² + 5x² - 45

= x²(x² - 9) + 5(x² - 9)

= (x² - 9)(x² + 5)

= (x - 3)(x + 3)(x² + 5)