That took them three points clear of Ange Postecoglou's Celtic, the only other team with a 100 per cent record. Celtic visit Kilmarnock on Sunday.
Malik Tillman opened the scoring for Rangers at Ibrox on Saturday just over half an hour in.
Rangers added three in the second-half, with Antonio Colak scoring the second before two quickfire goals from Scott Arfield and Tom Lawrence in the final 10 minutes put the game to bed.
Two quick second-half goals saw Motherwell come back to win their second game of the season after beating Aberdeen 3-2.
Blair Spittal put Well in front 20 minutes into the game, but Bojan Miovski's header levelled the score just before the break.
The opening 10 minutes of the second half saw three goals scored as Jonny Hayes put Aberdeen in front two minutes in.
Their lead was short-lived when Callum Slattery equalised and his goal was quickly followed by one from Kevin van Veen, who secured the three points for Motherwell.
A late goal from Ayo Obileye made it back-to-back wins for Livingston as they won 2-1 against Hibernian.
The Lions took an early lead through Joel Nouble six minutes in, but Nohan Kenneh pulled one back just after half-time to level for Hibs.
Just as the points looked to be shared, Sean Kelly's free-kick in the 86th minute found Obileye, who headed home from close range to score the winning goal.
St Mirren earned their first win of the season with a 1-0 win against Ross County.
Richard Tait scored the only goal of the game with a curling effort into the top corner, meaning County remain rooted to the bottom of the table.
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