Problem

Plot of y equal f of x with a shaded region between x = 2 and x = 6.

If you know that the area of the shaded region is 40 square units, which of the following can you evaluate?

  • \(\int_2^6 (f(x) + 5) \ dx\)

  • \(\int_2^6 (f(x) - 3) \ dx\)

  • \(\int_0^4 f(x + 2) \ dx\)

  • \(\int_2^6 f(x + 2) \ dx\)

  • \(\int_4^8 f(x + 2) \ dx\)

  • \(\int_2^6 -f(x) \ dx\)

  • \(\int_2^6 f(-x) \ dx\)

If there are any that you cannot evaluate, what additional information would you need in order to do so?

Can you find the value of the constant \(k\) for which

\[\int_2^6 (f(x) + k) \ dx = 0\]


How does your thinking change if instead you start with this image, in which the shaded area is 8 square units?

Plot of y equal g of x which is a straight line through the origin and a shaded region between x = 2 and x = 6.

Which of the integrals above can you evaluate for the linear function \(g(x)\)?

  • How does this compare to your answer for \(f(x)\)?

  • What makes this function different from \(f(x)\)?

  • What else do you know about \(g(x)\)?