Tìm GTLN của biểu thức: A = 5 + 2xy + 14y – x^2 – 5y^2 – 2x
Giải thích
A=5+2xy+14y–x2–5y2–2x =–x2–5y2+2xy–2x+14y+5 =−x2−2xy−2x+y2−2y+1−4y2+12y−9+15 =−x2−2xy−1+y2−2y+1−2y−32+15 =−x2−2xy−1+y−12−2y−32+15 =−x−y+1−22y−32+15
A=5+2xy+14y–x2–5y2–2x =–x2–5y2+2xy–2x+14y+5 =−x2−2xy−2x+y2−2y+1−4y2+12y−9+15 =−x2−2xy−1+y2−2y+1−2y−32+15 =−x2−2xy−1+y−12−2y−32+15 =−x−y+1−22y−32+15