\(4x\left(x^2-5\right)-\left(2x-3\right)\left(2x^2+x-8\right)=4x^2+20\)
\(4x^3-20a-\left(4x^3+2x^2-16x-6x^2-3x+24\right)=4x^2+20\)
\(4x^3-20x-4x^3+4x^2+19x-24=4x^2+20\)
\(4x^2-x-24-4x^2-20=0\)
\(-44-x=0\)
\(x=-44\)
BÀI 6 tìm x
1,\(2x\left(x-5\right)-\left(3x+2x^2\right)=0\) 2,\(x\left(5-2x\right)+2x\left(x-1\right)=13\)
3,\(2x^3\left(2x-3\right)-x^2\left(4x^2-6x+2\right)=0\) 4,\(5x\left(x-1\right)-\left(x+2\right)\left(5x-7\right)=6\)
5,\(6x^2-\left(2x-3\right)\left(3x+2\right)=1\) 6,\(2x\left(1-x\right)+5=9-2x^2\)
Chứng minh giá trị của x ko phụ thuộc vào giá trị của biến\(D=\left(5x2\right)^2-\left(6x+1\right)^2+11\left(x-2\right)\left(x+2\right)-16\left(3-2x\right).\)
\(E=4x\left(x-3\right)-\left(x-5\right)^2-3\left(x+1\right)^2+\left(2x+2\right)^2-\left(4x-5\right)\)
\(V=\left(x^2-3\right)^3+9x^2\left(x^3-3\right)-\left(x^2-3\right)\left(x^4+3x^2+9\right)-20.\)
Tìm x
a)\(3x\left(2x+1\right)=5\left(2x+1\right)\)
b)\(\left(3x-8\right)^2=\left(2x-7\right)^2\)
c)\(\left(4x^2-3x-18\right)^2-\left(4x^2+3x\right)^2=0\)
d)\(\left(9x^2-16\right)^2-4\left(3x+4\right)^2\)
e)\(\left(2x-1\right)\left(4x^2+2x+1\right)=x\left(x-8\right)\)
BT2: Tính giá trị biểu thức
\(M=\left(7-2x\right)\left(4x^2+14x+49\right)-\left(64-8x^3\right)\)tại \(x=1\)
\(P=\left(2x-1\right)\left(4x^2-2x+1\right)-\left(1-2x\right)\left(1+2x+4x^2\right)\)tại \(x=10\)
Bài 2 . Thực hiện phép tính
a)\(6x^3\)\(\left(\dfrac{1}{3}x^2-\dfrac{5}{2}-\dfrac{1}{6}\right)\)\(-2x^5\)\(-x^3\)
b)\(\left(x-3\right)\left(x^2+3x-2\right)\)
c)\(\left(4x^3-4x^2-5x+4\right):\left(2x+1\right)\)
Tìm x biết :(đề không sai )
1.\(-4x\left(x-7\right)+4x\left(x^2-5\right)\) \(=28x^2-13\)
2.\(\left(4x^2-5x\right)\left(3x+2\right)-7x\left(x+5\right)\) \(=\left(-4+x\right)\left(-2x+3\right)+12x^3+2x^2\)
3.\(\left(-4x^2-3\right)\left(2x+5\right)\) \(-\left(8x-3\right)\left(-x^2+2\right)\) \(-5x\left(x-6\right)-3x^2-4\)
4.\(\left(x-7\right)\left(x+5\right)-\left(x-3\right)\left(x-2\right)\) \(=15x^2\left(x+1\right)-\left(3x^2-1\right)\) \(\left(5x^2-2\right)-21x^2\)
5.\(\left(x-3\right)\left(-x+10\right)+\left(x-8\right)\left(x+3\right)\)\(=\left(5x^2-1\right)\left(x+3\right)-5x^3-15x^2\)
6.\(\left(-2x^2+5\right)\left(-x+3\right)-x^2\left(2x-6\right)\) \(=\left(x-1\right)\left(x+1\right)-\left(x-2\right)\left(x+4\right)\)
tìm x, biết:
\(a,-4x\left(x-7\right)+4x\left(x^2-5\right)\)\(=28x^2-13\)
\(b,\left(4x^2-5x\right)\left(3x+2\right)-7x\left(x+5\right)\))\(=\left(-4+x\right)\left(-2x+3\right)+12x^2+2x^2\)
Tìm x biết :
a)\((x+3)^2-\left(2x+1\right).\left(2x-1\right)=22\)
b)\(\left(4x+3\right).\left(4x-3\right)-\left(4x-5\right)^2=46\)
Chứng minh các biểu thức sau không phụ thuộc vào biến x:
a/ \(2x^2\left(4x+1\right)-8x^2\left(x+1\right)-\left(2x\right)^3-2x+3\)
b/ \(x\left(3x+12\right)-\left(7x-20\right)+x^2\left(2x-3\right)-x\left(2x^2+5\right)\)
