Answer:
[tex]\boxed{\,\bold{y=-6\left(x-\frac14\right)^2+\,\frac{19}8}\,}[/tex]
Step-by-step explanation:
[tex]y= -6x^2 +3x+2\\\\y=-6\big(x^2-\frac16\cdot3x-\frac16\cdot2\big)\\\\y=-6\big(x^2-\frac12x-\frac13\big)\\\\ y=-6\big(\underline{x^2-2\cdot x\cdot\frac14+(\frac14)^2}-(\frac14)^2-\frac13\big)\\\\ y=-6\big((x-\frac14)^2-\frac1{16}-\frac13\big)\\\\ y=-6(x-\frac14)^2+\frac38+2\\\\ \underline{y=-6(x-\frac14)^2+\frac{19}8}[/tex]