It was the first time the Rangers hit three straight homers since May 28, 1999 at home against Minnesota. Gonzalez hit the first homer of his major league career.
Nix recorded his second career multi-homer game, delivering a pair of two-run shots for Texas. Kevin Mench also homered for the Rangers.
Seattle scored three times in the top of the sixth to close within 9-6, but the Rangers teed off against Jarvis in the bottom half. Barajas and Gonzalez followed Nix's two-run homer with solo shots to make it 13-6.
Carlos Almanzar (2-0), the second of three Texas pitchers, recorded the win with 2 1/3 scoreless innings in relief.
Seattle starter Ryan Franklin (1-1) gsvr up seven runs and nine hits in 2 2/3 innings.