Respuesta :

sqdancefan

Substituting, we have

... f(x+4) = (x+4)² + 8(x+4) +7

... = x² +8x +16 +8x +32 +7

... = x² + 16x + 55

Subtracting the original, we have

... f(x+4) - f(x) = (x² +16x +55) -(x² +8x +7)

... f(x+4) - f(x) = 8x +48