Question

Tentukan hasil perkalian bentuk aljabar berikut!
a. –3b (6b² – 5ab)
b. (2y + 5)(y – 3)
c. (3× + 8y)(3× – 8y)
d. (3× + 7y)(2× + 5y)
e. (× + 2)(ײ – 2× + 5)

Answer 1

A) -3b.6b² + (-3b).(-5ab) = -18b^3 + 15ab²

b) 2y.y+2y.(-3)+5.y+5.(-3)
= 2y²-6y+5y-15
= 2y²-y-15

c) 3x.3x+3x.(-8y)+8y.3x+8y (-8y)
= 9x²-24xy+24xy-64y²
= 9x²-64y²

d) 3x.2x+3x.5y+7y.2x+7y.5y
= 6x²+15xy+14xy+35y²
= 6x²+29xy+35y²

e) (x+2).(x²-2x-5)
= x.x² + x.(-2x) + x.(-5) + 2.x² + 2.(-2x) + 2.(-5)
= x^3 - 2x² -5x + 2x² - 4x -10
= x^3 -2x²+ 2x² - 5x - 4x -10
= x^3 - 9x - 10

Answer 2

a. -3b (6b² - 5ab)
= (-3b × 6b²) (-3b × -5ab)
= -18b³ + 15ab²

b. (2y + 5) (y - 3)
= (2y × y) (2y × -3) (5 × y) (5 × -3)
= 2y² - 6y + 5y - 15
= 2y² - y - 15

c. (3x + 8y) (3x - 8y)
= (3x × 3x) (3x × -8y) (8y × 3x) (8y × -8y)
= 9x² - 24xy + 24xy - 64y²
= 9x² - 64y²

d. (3x + 7y) (2x + 5y)
= (3x × 2x) (3x × 5y) (7y × 2x) (7y × 5y)
= 6x² + 15xy + 14xy + 35y²
= 6x² + 35y² + 29xy

e. (x + 2) (x² - 2x + 5)
= (x × x²) (x × -2x) (x × 5) (2 × x²) (2 × -2x) (2 × 5)
= x³ - 2x² + 5x + 2x² - 4x + 10
= x³ - 2x² + 2x² + 5x - 4x + 10
= x³ + x + 10