h=gt1t2h=g t_{1} t_{2}h=gt1t2
12gt1t2\frac{1}{2} \mathrm{gt}_{1} \mathrm{t}_{2}21gt1t2
g(t1+t2)g\left(t_{1}+t_{2}\right)g(t1+t2)
g(t1+t2)2g\left(t_{1}+t_{2}\right)^{2}g(t1+t2)2