Question

x^4-5x^2-36
factorise

Answer 1

Answer:(x^2-9)(x^2+4)

Step-by-step explanation:

x^4-5x^2-36

=x^4-9x^2+4x^2-36

=x^2(x^2-9)+4(x^2-9)

=(x^2-9)(x^2+4)

Answer 2

Answer:

X^4-5x^2-36 = 0

put x^2 = t

t^2 - 5t - 36 = 0

t^2 + 4t - 9t - 36 = 0

t(t + 4) - 9(t + 4) = 0

(t + 4) (t - 9) = 0

t + 4 = 0 or t - 9 = 0

t = -4 or t = 9

resubstitude t = x^2

x^2 = -4 or x^2 = 9

take squareroot

x = +- 2 or x = +-3

Step-by-step explanation: