Tolong dibantu yaa . Perlu kali :)

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35. fungsi turun jika f' (x) < 0
f(x) = 1/3 x³ - x² -24x  +5
f '(x) < 0
x² - 2x - 24 < 0
(x - 6)(x+4) < 0
x < 6 atau x > - 4
atau -4 < x < 6

36. y = x³+2x² + 1
absis x = 1 --> y = 1+2+1 = 4
titik singgung (x1,y1) = (1,4)
gradien m = y' =  3x² + 4x
x = 1 --> m = 3+4 = 7
pers gasing --> y-y1 = m(x-x1)--> y -7x + 3 = 0

37. ∫(2x -3)² dx = ∫4x²- 12x + 9 dx = ⁴/₃ x³- 6x² + 9x + c

38. ₁³∫ x² + 4x - 2 dx = 1/3 x³ + 2x² - 2x ]³₁
= 1/3 (26)+ 2(8)-2(2)
= 26/3 + 12
=  62/3 = 20 ²/₃ satyuan

39. Luas y = x² dan y = 2x + 3
x² = 2x + 3
x² -2x - 3 = 0
a =1, b = -2 , c = - 3
D = b²-4ac= (-2)²- 4(1)(-3) = 16
Luas = D√D/ ( 6. a²)  = 16√16 / (6) = 64/6 = 10 ²/₃ satuan