Question

2x⁴+ax³-3x²+5x+b per x²-1 bersisa 6x+5 . nilai a-b =...?
a.-6
b.-3
c.1
d.6
e.8

Answer 1

Suku banyak tersebut dibagi (x + 1)(x - 1) bersisa 6x + 5
artinya
f(1) = 6(1) + 5 = 11
f(-1) = 6(-1) + 5 = - 1

f(1) = 11
2 + a - 3 + 5 + b = 11
a + b = 7

f(-1) = - 1
2 - a - 3 - 5 + b = - 1
- a + b = 5

eliminasi:
a + b = 7
- a + b = 5
_________ _
2a = 2
a = 1
b = 6
a - b = - 5
optionnya kurang tepat