QUIZ #028-2022Tentukan nilai a+b______________​

limit

lim x→-4 (4x² + 4x – 8)/(ax² + bx + 8) = 9/5

◆ substitusi langsung

(4(-4)² + 4(-4) – 8)/(a(-4)² + b(-4) + 8) = 9/5

40/(16a – 4b + 8) = 9/5

10/(4a – b + 2) = 9/5

4a – b + 2 = 50/9 … (1)

◆ L'Hop

lim x→-4 (8x + 4)/(2ax + b) = 9/5

(8(-4) + 4)/(2a(-4) + b) = 9/5

b – 8a = -140/9 … (2)

4a – b = 32/9

b – 8a = -140/9__(+)

-4a = -12

a = 3

4a – b = 32/9

b = 12 – 32/9

b = 76/9

a + b

= (27 + 76)/9

= 103/9