My students receive the wrong answer on their calculators when performing an integral with absolute value. Students with a competitor calculator do receive the correct answer. I included a screen shot to show you what's happening. I'm using the HP Prime app but I confirm the same thing happens with the handheld device.
The correct answer should be 4k. Is there any way this can be fixed?
The image that I attached should have the same result.
However, they do not.
Look closely, I have computed the same integral but I received different results. Putting the k inside the integral vs without should not yield different answers. In fact, if I compute a numeric answer, I still get something incorrect. See the following 3 images.
In the purely numeric answer, I receive a 3 from the HP Prime. I receive a 9 from Wolfram Alpha. This is a major problem. If you compute this numerically using an approximation of boxes, you'll see that the answer is indeed 9.
The HP Prime computes an incorrect answer. This could be deeply problematic for students taking a Calculus BC exam or if they are in classes (like mine) of Calculus III.
I read the message. The arguments you are supplying are real. It says correct if real arguments, which they are. No complex numbers are being used for any of these integrals. Cosine has no singularities at all (it's continuous over all reals) and there are no discontinuities. The messages provided do not discuss why the answers are different.
Try the numeric one I posted above where you receive an answer of 3 as opposed to 9 by Wolfram Alpha or the TI nSpire CX CAS.