Paving the way in tone if not substance for the nationwide speech her husband will make Sunday night, Rosalynn Carter yesterday told 1,200 Democratic women at a White House tea that "quick fixes" aren't the answer to what ails America. And she implored them to lend support in "educating" the people about some sacrifices ahead.

"We've tried quick fixes and they may help a little bit in an election time, but over the long run quick fixes don't work," she said, standing in the 90-degree heat on the South Lawn.

Describing the president as "optimistic that we can solve any problem," the first lady said people he has been consulting in his Camp David seclusion see the problems as being deeper than the country's energy deficiencies.

"Everybody recognizes also that these are not problems that just came upon us - they are problems that have developed over a long number of years."

Citing "many past victories," specifically civil service reform and the Panama Canal treaties, she said, "We remember other times of crisis when we have always stood, we have always strong and we always prevailed."

Later, in an impromptu receiving line inside the White House, Mrs. Carter respondend to a reporter's question about whether her husband was returning with a solution.

"I don't know if there is any one solution, but we can do it," she said. "We'll try something and if it doesn't work, we'll try something else."

A White House spokesperson said the event was a "first" for the Woman's National Democratic Club whose entire 2,100 members had been invited. Some members came from Tennessee, Illinois, Georgia, Pennsylvania and New York. One woman cut short her vacation in Singapore so that she could attend.

The line started forming at 1 p.m. along East Executive Avenue even though invitations had clearly stated arrival time as an hour later. Some guests wore floppy hats and braved the broiling sunshine; other sought refuge in air conditioned rooms inside the mansion.

On the lawn where a red and white striped tent shaded the refreshment stand, waiters did a frenzied business in iced tea (sherry was served in the house).

Out of view, virtually unnoticed, was Amy Carter, her blond hair newly shorn, posing for an official photograph. Not so out-of-view as he headed toward the tennis courts, Vice President Mondale, dressed in tennis whites, peeked around his unidentified partner.

On stage with Mrs. Carter were Joan Mondale and WNDC President Carol Williams. In the crowd were HUD Secretary Patricia Harris, Pamela Harriamn, Polly Shackleton, Jane Wirtz, Mary Louise Day and Frances Humphrey Howard.

Howard called it "a very good speech that reached out - she wasn't pleading. She knows we can take on an excellent role of leadership."

Roscoe Dellums said: "Maybe we are a lobbying group now. I think it's smart to invite a large cohesive organization like this. I don't think we're being exploited."

One member, Donna Shor, said: "We're the group she should call on. This is family." CAPTION: Picture, From left, Rosalynn Carter, Carol Williams and Joan Mondale, by Margaret Thomas