solve

Question

Y^4 - 3y^2 - 4 = 0?

Answer 1

The equation is y⁴ - 3y² - 4 = 0.

Let y² = t, then the equation is t² - 3t - 4 = 0.

By factoring by grouping.

t² - 4t + t - 4 = 0

t(t - 4) + 1(t - 4) = 0

(t - 4)(t + 1) = 0

Apply zero product property.

t - 4 = 0 and t + 1 = 0

t = 4 and t = - 1

Put t = y².

y² = 4 and y² = - 1

y = ± 2 and y = ± i.

The solutions are y = ± 2 and y = ± i.