bantu lagi yah semoga pahalanya berlipat ganda

6. a. f(0) = 0-0+3 = 3
b. f(10) = 100-40+3 = 63
c. f(15) = 225-60+3 = 168

7. 4x + 3y = -9 (dikali 1)
2x - y = 13 (dikali 2)
--------------
4x + 3y = -9
4x - 2y = 26
-------------- -
5y = -35
y = -7
2x + 7 = 13
2x = 6, x = 3
(x0, y0) = (3, -7)
2x0 + 2y0 = 6 - 14 = -8

8. -x² + 6x - 5 = 7 - 2x
-x² + 8x - 12 = 0
x² - 8x + 12 = 0
(x - 6)(x - 2) = 0, ketemu x = 2 dan x = 6
x = 2 → y = 7 - 4 = 3
x = 6 → y = 7 - 12 = -5
(x, y) = {(2, 3), (6, -5)}

9. A - 7 = 6(B - 7) → A - 7 = 6B - 42
A = 6B - 35
2(A + 4) = 5(B + 4) + 9
2A + 8 = 5B + 20 + 9 = 5B + 29
2A = 5B + 21 = 12B - 70
12B - 5B = 21 + 70
7B = 91
B = 13
A = 6×13 - 35
= 78 - 35 = 43 tahun

10. sin A = 12/13 = depan/miring
samping = √(169-144) = √25 = 5
a. tan A = depan/samping = 12/5
cos A = samping/miring = 5/13

cos B = 24/26 = 12/13 = samping/miring
depan = √(169-144) = √25 = 5
b. sin B = depan/miring = 5/13
tan B = depan/samping = 5/12