Penjelasan dengan langkah-langkah:

1. –x² + 7(x – 3) = 0

–x² + 7x – 21 = 0

a = –1, b = 7, c = –21

2. x² – 7x + 12 = 0

(x – 3)(x – 4) = 0

x1 = 3

x2 = 4

2x1 + 5x2 = 2×3 + 5×4

2x1 + 5x2 = 6 + 20

2x1 + 5x2 = 26

3. 3x² – 5x + 6 = 0

Diskriminan ( D) = b² – 4ac

D = (–5)² – 4(3)(6)

D = 25 – 72

D = –47

5. (p – 4)x² + 3x + 5 = 0

grafik terbuka ke atas, → a > 0

p – 4 > 0

p > 4

6. 2x + 4y = 8

titik potong sumbu y → x = 0

2(0) + 4y = 8

0 + 4y = 8

y = 8/4

y = 2

tipot y → (0, 2)

7. f(x) + g(x) = –4x² – x + 3 + 6x – 10

f(x) + g(x) = –4x² + 5x –7

9. (f o g)(x) = f(g(x))

(f o g)(x) = f(x + 2)

(f o g)(x) = –2(x + 2)² + 1

(f o g)(x) = –2(x² + 4x + 4) + 1

(f o g)(x) = –2x² – 8x – 7