y=12/11x²-43/11x-5=12/11(x²-43/12x)-5=12/11(x²-2×43/24x+43/24²-43/24²)-5=12/11[(x-43/24)²x-43/24²]-5=12/11(x-43/24)²-1849/22-5=12/11(x-43/24)²-1959/22