Sederhanakanlah bentuk aljabar berikut : a) 9x + by - 10y -8x b) x² + 8y² - 16 + 10x² - 7y² +11 c) 18a - 5 (a - 3b) d) 12 + 2 (4x - 3) e) a (a + 3b) + 2a (4a +5

a)
9x + by - 10y - 8x
= 9x - 8x + by - 10y
= x + (b - 10)y

b)
x² + 8y² - 16 + 10x² - 7y² + 11
= x² + 10x² + 8y² - 7y² - 16 + 11
= 11x² + y² - 5

c)
18a - 5(a - 3b)
= 18a - 5a + 15b
= 13a + 15b

d)
12 + 2(4x - 3)
= 12 + 8x - 6
= 8x + 12 - 6
= 8x + 6

e)
a(a + 3b) + 2a(4a + 5b)
= a² + 3ab + 8a² + 10ab
= a² + 8a² + 3ab + 10ab
= 9a² + 13ab