Ta có: \(\left(4x+2\right)\left(7-3x\right)+\left(x-5\right)\left(12x+4\right)\)
\(=28x-12x^2+14-6x+12x^2+4x-60x-20\)
\(=-34x-6\)
Bài 3: Áp dụng đẳng thức trên thực hiện phép nhân bằng cách cho a, b là một số cho trước. ( mỗi ý 10 câu, rồi tính...) Hãy tính:
1) ( x+3)( x+ 5) =
2) (x+6)(x+2)
3) (x+3)(x+7)
4) ( x- 3)( x-5)
5) (x-4)(x-9)
6) (x-10)(x-12)
7) (x+3)(x-5)
8) (x_8)(x+3)
9) (x+8)(x-4) 10) ( 2x-1)( 3x-2)
11)(3x+1)( 5x-3)
Tính(rút gọn)
1, x^ 2 - 2x + 5 - (x - 7)(x + 2)
2,-5x(x-5)+(x-3)(x^2-7)
3, x(x^2-x-2)-(x+5)(x-1)
4, (-x+5)(x+3)+(2x-1)(x+3)
5, -4x(x+3)(x-4)-3x(x^2-x+1)
1. (2x +3) (x- 5) +(X-4 ) + (x-5) ( x-2 0 = (3x -5) ( x-4)
2. (8x-3) (3x +2) - (4x+ 7) (x+4) = (2x + 1) (5x-1)
3. 2x^2 + (x -1) (x+1)= 5x (x+10
4. 4- ( x-1) (x+5) - (x+2) (x+5) = 3(x-1) (x+2)
1) 5(x-3) (x-7)-(5x+1) (x-2)= -8
2) x(x+1) (x+2)-(x+4) (3x-5)= 84-5x
3) (9x2-5) (x+3)-3x2(3x+9)=(x-5) (x+4)-x(x-11)
4) (x2-4x+16) (x+4)-x(x+1) (x+2)+3x2=0
5) (8x+2) (1-3x)+(6x-1) (4x-10)=-50
6) (x2+2x+4) (2-x)+x(x-3) (x+4)-x2+24=0
7) (\(\dfrac{x}{2}\)+3) (5-6x)+(12x-2) (\(\dfrac{x}{4}\)+3)=0
1) (\(\dfrac{1}{2}\)x + 3)*(x2- 4x- 6)
2) (6x2 -9x +15)*(\(\dfrac{2}{3}\)x+1)
3) (3x2 -x+5)*(x3+5x-1)
4) (x-1)*(x+1)*(x-2)
5) D=(x-7)*(x+5)-(x-4)*(x+3)
6) E= 4x*(x2-x-1)-(x+3)*(x2-2)
7) F= 5x*(x-3)*(x-1)-4x*(x2-2x)
Bài 1
1) (x^2-2x+3)*(x-4)
2) (2x^2-3x-1)*(5x+2)
3) (x^2-2xy+y^2)*(y^2+2xy+x^2+1)
4) (x-7)*(x+5)*(x-5)
5) (x+2y)*(x-y)
6) (x+5)*(x^2-2x+3)
7) 2x(x+5)*(x-1)
8) (x-2y)*(x+2y)
9) (x-1)*(x^2+x+1)
10) (1-2x^2+x)*(x-4+x^2)
Chứng minh biểu thức sao ko phụ thuộc vào biến
a)(3x-1).(2x+7)-(x+1).(6x-5)-(18x-12)
b)(2-x).(1+2x)+(1+x)-(x4+x3-5x2-5)
c)(x2-7).(x+2)-(2x-1).(x-14)+x.(x2-2x-22)+35
Gíup mk nha các bn
5) D=(x-7)*(x+5)-(x-4)*(x+3)
6) E= 4x*(x2-x-1)-(x+3)*(x2-2)
7) F= 5x*(x-3)*(x-1)-4x*(x2-2x)
Bài 1.Tìm x biết
a,(x+8)(x+6)=104+x^2
b,(x+1)(x+2)-(x-3)(x+4)=6
c,4x(x-5)-(x-1)(4x-3)=5
d,(3x-4)(x-2)=3x(x-9)-3
e,(x-5)(x-4)-(+1)(x-2)=7
f,5x(x-3)=(x-2)(5x-1)-5
