Treasury secretary backs budget in appearance . . .

Speaking before the House Appropriations Committee Tuesday, Treasury Security Donald Regan defended President Reagan's $848.5 billion 1984 budget. Secretary Regan said the budget would create 1.4 to 1.7 million new jobs.

He also said recovery from the recession ''may well already be under way'' and warned Congress against overstimulating the economy in an effort to speed the process.