Merge pull request #316 from APEXCalculus/integration_fix

Update sec_antider.ptx

ptx/sec_antider.ptx

@@ -374,7 +374,7 @@
         </p>
         <p>
           <md>
-            <mrow>\amp\lzoo{x}{cf(x)}=c\cdot\fp(x)\amp\amp\int c\cdot f(x)\,dx= c\cdot \int f(x)\,dx</mrow>
+            <mrow>\amp\lzoo{x}{cf(x)}=c\cdot\fp(x)\amp\amp\int c\cdot f(x)\,dx= c\cdot \int f(x)\,dx\quad(c\neq 0)</mrow>
             <mrow>\amp\lzoo{x}{f(x)\pm g(x)} =\fp(x)\pm g'(x)\amp\amp \int \big(f(x)\pm g(x)\big)\,dx =\int f(x)\,dx\pm \int g(x)\,dx</mrow>
             <mrow>\amp\lzoo{x}{C} = 0\amp\amp \int 0\,dx = C</mrow>
             <mrow>\amp\lzoo{x}{x} = 1\amp\amp \int 1\,dx = \int dx = x+C</mrow>