Question

Suku keempat dari (x-2y)^10 adalah
a.-240x^7y³
b.120x³y³
c.960x³y³
d.-960x^7y³
e.240x^7y³

Answer 1

Sama artinya dengan :
10C3 (x)^(10-3) (-2y)^3
= 10!/(7!3!) (-2)^3  x^7y^3
= 10.9.8.7!.(-8) / (7!3!)  x^7y^3
= -960 x^7y^3

Answer 2

(x -2y)¹°
= 1a¹° -10a⁹b +45a⁸b² -120a⁷b³ +210a⁶b⁴ -252a⁵b⁵ +210a⁴b⁶ -120a³b⁷      +45a²b⁸ -10ab⁹ +1 b¹°

= 1(x)¹° +10(x)⁹ (-2y) -45(x)⁸(-2y)² +120(x)⁷(-2y)³ -210(x)⁶(-2y)⁴ +252(x)⁵(-2y)⁵ -210(x)⁴(-2y)⁶ +120(x)³(-2y)⁷ -45(x)²(-2y)⁸ +10(x)(-2y)⁹ -1(-2y)¹°

= x¹°-20x⁹y -180x⁸y² -960x⁷y³ -840x⁶y⁴ +.....................................

Jadi, jawabannya adalah  -960x⁷y³ (c.).
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