Question

Yg pintar MTK

Nomor 2 bagian B

Yg benar jawaban terbaik

Answer 1

F(x) = 2x² + 7x - 15
→ untuk x = 1/2, maka
f(1/2) = 2(1/2)² + 7(1/2) - 15
= 2(1/4) + 7/2 - 15
= 2/4 + 7/2 - 15
= 1/2 + 7/2 - 15
= 8/2 - 30/2
= -22/2
= -11

→ untuk x = 1/a² - 1, maka
f(1/a²- 1) = 2(1/a² - 1)² + 7(1/a²-1) - 15
= 2/(a² - 1)² + 7/(a² - 1) - 15(a² - 1)²/(a² - 1)²
= 2 + 7a² - 7 - 15(a^4 - 2a² + 1) / (a² - 1)²
= -5 + 7a² - 15a^4 + 30a² - 15 / (a² - 1)²
= -15a^4 + 37a² - 20 / (a² - 1)²