To make any decimal into and exact value (i.e 0.87676) do you just divide it by 1000........ the number of zero's depending on how many zero's the number has? My teacher said something along these lines but the SAC is tommrorw and cannot seem to contact him
No. An "exact value" isn't a fraction, an exact value is the EXACT thing that something is equal to. For example, if you have a 1 metre ruler, then it has an "exact value" length of 1m. If you cut it in half, it has an "exact value" length of 0.5m. You can write it as a half, but that doesn't mean 0.5 is any less exact.
How do you get exact values on CAS without using the exact function on the CAS. My teacher said not to use exact CAS function as it’s not accurate, but I can’t remember how he said to do it?
For example I got 1.39 as x- intercept so I just put 139/100 for exact. However in the solutions they got loge(4) with is equivalent to 1.39.....am I wrong?
Yes, and this comes to confusion as to what exact means. In this case, the EXACT solution is ln(4). ln(4) is APPROXIMATELY equal to 1.39 - but that's bigger than ln(4) is EXACTLY equal. A better approximation is 1.386, and a BETTER approximation again is 1.3863, and an EVEN BETTER one again is 1.38629 and... you get the idea.
At some point in the method you've used, you've made a numerical approximation. To know where, I'd have to see your method. However, you are wrong, because the idea that fractions are exact values is wrong - just because you've turned something into a fraction, doesn't make it exact.