Someone in Microsoft’s Answers forum wrote that the Microsoft Math Add-in doesn’t seem able to handle equations like this one:
Indeed, when I insert that equation into an equation container in Word 2010, then choose Compute – Solve, this is what I see:
The Math add-in does not handle multi-character variable names done in that way. Instead, it treats “total BTUH” as t*o*t*a*l*B*T*U*H. What fun!
An awkward but possibly-acceptable work-around is to substitute single-letter variables,
Now, Math offers the following choices:
It will also let you graph in 3D:
But, note that the choices of letters are important, since Math has some pretty set ideas about where x, y, and z belong in a 3D graph, as well as what specific letters mean. If I arbitrarily assign different letters, it ranges from not working at all to giving entirely different graphs.
Another route is to use _ to create multi-character variable names. If we try to let the variables resemble the original names, such as choosing:
Solve now works correctly:
But, now all of the choices for Graph are grayed out:
And, as usual… YMMV (your mileage may vary).