如图所示的电路中，电源电压为30V，定值电阻为30Ω，滑动变阻器标有“60Ω 1.5A”字样，在该电路正常使用的情况下，则（　　）

若x₁，x₂是一元二次方程x²+4x﹣2016=0的两个根，则x₁+x₂﹣x₁x₂的值是（　　）

If you are not happy with China's high Internet fees and slow speed, you are not alone. So is Premier Li Keqiang. On April 14, he said in a meeting that the government should speed up the Internet and lower the fees.

“The first question people ask at a new place is 'Is there WI-FI' because Internet service fees are so high,” said Premier Li. According to a recent survey by CCTV, the average cost of 1GB mobile Internet data per month in China is 100 Yuan, while it is only 60 Yuan in the US and 40 in Japan.

However, high prices don’t necessarily mean good service. The average Internet speed in China was 4.25Mbps（兆比特每秒）in late 2014. South Korea had the fastest average Internet speed-25.3 Mbps. People can download a 1 GB movie within 6 minutes in South Koreas, but in China it would take half an hour.

To improve Internet services, the key is to build more fiber(光纤) networks. Through them we can send text, pictures and videos globally in less than a second, which offer high speed Internet. Besides, the lack of market competition is another problems. Having more operators（运营商）besides China Unicom and China Telecom may lower the prices.