And it's because this variable here is not the same as the variables on which we are integrating.

因为这个变量，和积分的变量不一样。

youdao

OK, so here, we are integrating first over u.

,我们将先对u积分。

youdao

The challenge here is in the complexity and cost of integrating all this in a seamless way, both on the technological as well as corporate side.

挑战在于，在技术和企业两个层面让一切实现无缝融合是很复杂的，而且成本很高。

youdao

"We first met with the team at Cardio when we were working on integrating their technology into the Paypal Here mobile app, " said Hill Ferguson, Paypal's vice president of global product, on the firm's blog.

BBC: Paypal buys the Cardio credit card scanning service