solve number 17

In Problems 15-22 determine whether the given functions are linearly inde- pendent or dependent on (-co, co). 15. fi(x) = x, f2(x) = x2, f3(x) = 4x - 3x2 16. f (x) = 0, f2(x) = x, f3(x) = ex 17. fi(x) = 5, f2(x) = cos x, f3(x) = sin2x 18. fi(x) = cos 2x, f2(x) = 1, f3(x) = cos2x 19. f (x) = x, f2(x) = x - 1, f;(x) = x+ 3 20. fi(x) = 2 + x, f2(x) = 2+ /x 21. fi(x) = 1 + x, f2(x) = x, f3(x) =x2 22. fi(x) = ex, fz(x) = e"*, f3(x) = sinh x