I have gotten mid-high Bs in two advanced math classes both semesters. If I take the math 2 subject test and do well, will it make up for the lower grades and show colleges that I am not bad at math?
Two b+ ‘s in advanced math like calc ab and bc is not bad. It’s actually really excellent. And a 4 or 5 would help support that but is not make or break.
I do not think that a subject test will make up for grades (1 hour test that can easily be studied for vs. 2 years of tests and other grades). But as the above poster said, high Bs are not bad grades, even though there may seem to be a different consensus on CC.
The vast majority of colleges do not even consider SAT subject tests in determining admission and thus taking the math 2 will mean nothing to them. For the colleges that require (there are only 6 such colleges left that require them of most applicants) recommend (about 18 colleges, counting the UCs as one), or neither require nor recommend but will consider subject tests if submitted (about 46 colleges), a high math 2 score can help but it is not likely to “make up” for bad math grades (except for the UCs and CalStates where a math subject test grade can be used in lieu of math grades to meet the math requirement needed for admission), but as mentioned yours are not bad.
Agree, SAT subject tests will not make up for a grade in a class. Many higher level math concepts (ex. calculus) are not covered in the SAT II.