Lỗi: An app on your pc needs the following windows feature .net framework 3.5

em co cai chuong trinh mathcad tren win 8, cai dc chut thi no hien hop thu thoai thong bao fai co net. framework 3.5....e tim thay trong file cai dat cua mathcad cung co file net.framework 3.5. nhung khi e mo chay thi hien thong bao nay va e chon cai nao cung k dc. nho moi ng giup e voi. ai dat ...

em co cai chuong trinh mathcad tren win 8, cai dc chut thi no hien hop thu thoai thong bao fai co net. framework 3.5....e tim thay trong file cai dat cua mathcad cung co file net.framework 3.5. nhung khi e mo chay thi hien thong bao nay va e chon cai nao cung k dc. nho moi ng giup e voi.ai dat net.frmework 3.5. xin cam on