Đặt a=x+5; b=2x-4
Ta sẽ có pt \(a^3+b^3=\left(a+b\right)^3\)
\(\Leftrightarrow a^3+b^3-a^3-b^3+3ab\left(a+b\right)=0\)
=>3ab(a+b)=0
=>(x+5)(2x-4)(3x+1)=0
hay \(x\in\left\{-5;2;-\dfrac{1}{3}\right\}\)
Bài 1. Tìm x, biết
a) (x+4)2-x2(x+12)=16
c) (x+3)3-x(3x+1)2+(2x+1)(4x2-2x+1)=28
d) (x-2)3-(x+5)(x2-5x+25)-6x2=11
Bài 2. Rút gọn các biểu thức sau:
A = (x+1)3+(x-1)3
B = (x-3)3-(x+3)(x2-3x+9)+(3x-1)(3x+1)
Tìm x, biết :
a) (x+4)2-x2(x+12)=16
c) (x+3)3-x(3x+1)2+(2x+1)(4x2-2x+1)=28
d) (x-2)3-(x+5)(x2-5x+25)-6x2=11
tìm x 4.(x+1).(-x+2)+(2x-1).(2x+3)=-11 (2x+4).(3x+1).(x-2)-(-3x2 +1).(-2x+2/3)=-26/3
1. (x-6)^2 = 2(x-6)
2. 2(x-3)^2 = (x-3)(x+5)
3. 4(x-3)=2x-5(2x+3)
4. x2 +4 -2 (x-1) = (x-2)^2
5. x-3/5 = 6 - 1-2x/3
6. x+2 = 6-5x/2
7. x+2/5 - x+3 = x-2/2
8. 2x-5/x-4 = 2x+1/x+2
9. X+3/x-3 - x-1/x+3 = x2 + 4x + 6/x2 -9
10. 3x-3/x2-9 -1/x-3 = x+1/x+3
11. X+1/x-1 - x-1/x+1 = 4/x2 -1
tìm x (2x+4).(3x+1).(x-2)-(-3x2 +1).(-2x+2/3)=-26/3
giải hộ mk câu c ạ mk lm sai ấy
(x-5)(x+5)-(x+3)^2+3(x-2)^2=(x+1)^2-(x-4)(x+4)+3x^2
bài tập 1: tìm x, biết
a) (x - 3)(x + 3) = (x - 2)2 - 1
b) (2x - 1)2 = (2x +5)(2x - 5) + 2
c) (x + 1)3 = x2(x - 2) + 5(x2 - 1
d) (x2 - 3x + 9)(x + 3) = (x - 2)3 + (3x - 1)(2x + 3)
bt1: tìm x, biết
a) (2x + 3)2 + (x - 1)(x + 1) = 5(x + 2)2 - (x - 5)(x + 1) + (x + 4)2
b) (x + 1)3 - (x + 3)(x2 - 3x + 9) = (x - 3)2 + 3(2x + 1)2 - (x3 - 5x + 1)
