2x^2-x+5,g(x)=x+1

2x^2-x+5,g(x)=x+1    assuming that the first function is f(x)

[f+g](x) means that we just add the functions together  = 2x^2 + 6

[f + g](6)  means that we "plug" 6 into what we've just found in the first part......so we have...... 2(6)^2 + 6  = 2(36) + 6 = 72 + 6 = 78

f(x)  =  2x² - x + 5                 g(x)  =  x + 1

(f + g)(x)  =  f(x) + g(x)  =   (2x² - x + 5) + (x + 1)  =  2x² + 6

(f + g)(6)  = 2(6²) + 6  =  78