Question

(x+1)! -2(x-1)! / (x+1)! +10(x-1)! = 7/10
Preciso de ajuda.

Answer 1

(x+1)(x)(x-1)! -2(x-1) / (x+1)(x)(x-1)! +10(x-1)! = 7/10
(x-1)! * [(x+1)(x) - 2] / (x-1)[(x+1)(x) + 10] = 7/10
(x+1)(x) -2 / (x+1)(x) + 10 = 7/10
x²+ x -2 / x² + x + 10 = 7/10
10x² + 10x -20 = 7x² + 7x + 70
3x² + 3x - 90 = 0
∆= 9 - 4*3*(-90)
∆= 1089
- 3 ± 33/ 6
x¹ = 5
x² = -6