式3: "y" Subscript, 2 , Baseline tilde "a" Subscript, 0 , Baseline "x" to the 0 power plus "a" Subscript, 1 , Baseline "x" to the 1st power plus "a" Subscript, 2 , Baseline "x" squared plus "a" Subscript, 3 , Baseline "x" cubed plus "a" Subscript, 4 , Baseline "x" to the 4th powery2~a0x02+a1x12+a2x22+a3x32+a4x42