1.
a) 2x(x-7) + (2x-2)(x+1)
= 2$x^{2}$ - 14x + 2$x^{2}$ + 2x - 2x - 2
= 4$x^{2}$ - 14x - 2
b) 4(x+3) + (x-4)(x-5)
= 4x + 12 + $x^{2}$ - 5x - 4x + 20
= $x^{2}$ - 5x + 32
2.
a) 3x(2x-1) - 2x(3x+2)
câu này thiếu đề ạ?
b) 6x(x +1)+6x+6=0
=> 6x(x+1) + 6(x+1) = 0
=> (x+1)(6x+6) = 0
TH1: x+1 = 0
=> x = -1
TH2: 6x + 6 = 0
=> 6x = -6
=> x = -1
Vậy: x = -1
c) 2x(5x+3) - x(3+10x) = 18
=> 10$x^{2}$ + 6x - 3x - 10$x^{2}$ = 18
=> 3x = 18
=> x = 6
Vậy : x =6
d) 2x(x-5) - 2x + 10 = 0
=> 2($x^{2}$ - 5x) - 2(x-5) = 0
=> 2($x^{2}$ - 5x - x + 5) = 0
=> $x^{2}$ - 6x = -5
=> x(x-6) = -5
TH1 : x = -5
TH2 : x-6 = -5
=> x = 1
Vậy:...
