Which of the following forms of h(x) reveals its minimum value without having to be rewritten?
1) h(x) = 5x² + 10x – 40
2) h(x) = 5(x + 4)(x - 2)
3) h(x) = 5 (x² + 2x – 8)
4) h(x) = 5(x + 1)² – 45