Given; ∫(0.6x + 1.35)dx
from the definition of integration
∫x^n dx = (1/{n+1}x^{n+1})
therefore
∫(0.6x + 1.35)dx = 0.3(x^2) + 1.35x
introducing the upper limit introducing the lower limit
= 0.3(6)^2 + 1.35(6) =0.6(0) + 1.35(0)
= 10.8 + 8.1 = 0
=18.9
therefore
∫(0.6x + 1.35)dx = 11.7 - 0 = 18.9