1.Jika A=2x+5y B=x-3y A.A+B B.A-B C.B-A D.3A-B E. AB 2.jika A=2x-7 B=-x+5 A.2a+3b B.AB C.A-B D.(2×-7)(-x+5) Memakai cara!!!

Mapel : Matematika
Kelas : VII SMP
Bab : Aljabar

Pembahasan :
1.

A + B = (2x + 5y) + (x - 3y)
A + B = (2 + 1)x + (5 - 3)y
A + B = 3x + 2y

A - B = (2x + 5y) - (x - 3y)
A - B = (2 - 1)x + (5 + 3)y
A - B = x + 8y

3A - B = 3(2x + 5y) - (x - 3y)
3A - B = 6x + 15y - x + 3y
3A - B = (6 - 1)x + (15 + 3)y
3A - B = 5x + 18y

AB = (2x + 5y)(x - 3y)
AB = (2x)(x) + (2x)(-3y) +(5y)(x) + (5y)(-3y)
AB = 2x² - 6xy + 5xy - 15y²
AB = 2x² - xy - 15y²

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2.

2A + 3B = 2(2x - 7) + 3(-x + 5)
2A + 3B = 4x - 14 - 3x + 15
2A + 3B = x + 1

AB = (2x - 7)(-x + 5)
AB = -2x² + 10x + 7x - 35
AB = -2x² + 17x - 35

A - B = (2x - 7) - (-x + 5)
A - B = 2x - 7 + x - 5
A - B = 3x - 12