Question

me ajudam por favor (2x²-5)²=39+10(2x²-5)
 

Answer 1

(2x²-5)² = 39 + 10(2x²-5)
4x⁴ - 20x² + 25 = 39 + 20x² - 50
4x⁴ -40x² +36 = 0, p/ x² = y
4y² - 40y + 36 = 0 (/4)
y² - 10y + 9 = 0, p/ a = 1; b = -10; c = 9
Δ = (-10)² - 4(1)(9) = 100 - 36 = 64
y´ = (-b + √Δ)/2a = (10+8)/2 = 9
y" = (-b - √Δ)/2a = (10 - 8)/2 = 1
..............
x² = y' => x² = 9 => x = +-3
x² = y" => x² = 1 => x = +-1
S={ -3, -1, 1, 3}