Can I configure a TP-LINK TL-WR740N as a repeater?

Yes you can configure your TP-Link WR740N as a repeater/wireless bridge. Following are the basic steps that you need to take to set up one:

• Go to wireless settings page of your WR740N router's web interface, enable the option "Enable WDS Bridging" and click Survey.
• Your bridge router will show you routers to bridge with. Select the appropriate one.
• Make sure that the selected security settings are the one that match with the router that is connected to the ISP and provide a password for it.
• Disable your bridge router's DHCP and restart the router.

Following these steps should allow you to set up your WR740N as a repeater. I have been using it as one without any problem so far.

Yes, you can!

According to this link provided by TP Link, you cand make the settings. I have multiple TP Link routers at home, all configured as WDS repeaters after this settings and entire network is working fine.

Follow this steps:

1. Login into root AP or extended AP and enable WDS under: Wireless -> Wireless Settings.
2. Click on Search/Survey button and click Connect to desired SSID Wireless Network.
3. On the password input, put your main SSID Wireless password (should be the same) and Save settings.
4. Disable DHCP under: Wireless -> Wireless Security.
5. Reboot router/AP.

Note:

1. LAN IP of extended router should be different but in the same subnet of the root router;
2. The DHCP Server on extended router should be disabled;
3. WDS bridging only requires the WDS setting on either the root router or the extended router.

note: The accepted answer is incorrect.

No, unfortunately you cannot. Your model only has one wireless interface, while a repeater needs two. A single card repeater will wnd up talking to clients half of the time, and to its base station the other half of the time, thus cutting bandwidth in half.

In fact, its User's Guide makes no mention of alternative modes like wireless repeater, range extender, wireless bridge, which are all roughly synonims.

The term WDS does indicate its ability to partake in a Wireless Distribution System, however I believe it is meant to indicate that it can act as a base station, not a relay-station as required by the OP. Besides, in the manual mentioned above, there is no discussion of WDSes.