Question

if 3x⁴+10x³-42x²+10x+3=0, then x+1/x=?​

Answer 1

Step-by-step explanation:

Divide both sidea by x²

3x²+10x-42+10/x + 3/x² = 0

3(x²+1/x²) + 10(x+1/x) - 42 =0

3{(x+1/x)²-2} + 10(x+1/x) - 42=0

Let x +1/x=t

3(t²-2) + 10t - 42=0

3t²-6+10t-42=0

3t²+10t-48=0

(t+6)(3t-8)=0

x+1/x=-6 or 8/3