Вправи: 412

412. Знайдіть координати вершини параболи.

1) y = x² – 12x; x₀ = 122 = 6;

y₀ = 36 – 12 • 6 = 36 – 72 = –36; (6; –36).

2) y = –x² + 5;

x₀ = 0; y₀ = 5; (0; 5).

3) y = 8x² – 2;

x₀ = 0; y₀ = –2; (0; –2).

4) y = x² – 14x – 90; x₀ = 142 = 7;

y₀ = 49 – 14 • 7 – 90 = 49 – 98 – 90 = –139; (7; –139).

5) y = x² + 2x + 1; x₀ = -22 = –1;

y₀ = 1 – 2 + 1 = 0; (–1; 0).

6) y = –4x² – 16x + 7;

x₀ = 1624 = -168 = –2;

y₀ = –4 • (–2)² – 16(–2) + 7 = –4 • 4 + 32 + 7 = –16 + 32 + 7 = 23;

(–2; 23).