What are the solutions of the equation 9x4 – 2x2 – 7 = 0? use u substitution to solve. x = + √7/9 and x = ±1 x = + √7/9 and x = ±i x = +i √7/9 and x = ±1 x = +i √7/9 and x = ±i

Step-by-step explanation:

9x⁴ – 2x² – 7 = 0

Let's say that u = x²:

9u² – 2u – 7 = 0

Factor:

(u – 1) (9u + 7) = 0

u = 1, -7/9

Since u = x²:

x² = 1, -7/9

x = ±1, ±i √(7/9)

n

step-by-step explanation:

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step-by-step explanation: