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\(\left(4x^4+4x^3-16x^2-16x\right):\left(4x+4\right)\)
\(=[\left(4x^4+4x^3\right)-\left(16x^2+16x\right)]:\left(4x+4\right)\)
\(=[4x^3.\left(x+1\right)-16x.\left(x+1\right)]:\left(4x+4\right)\)
\(=[\left(4x^3-16x\right).\left(x+1\right)]:\left(4x+4\right)\)
\(=[4.\left(x^3-4x\right).\left(x+1\right)]:[4.\left(x+1\right)]\)
\(=\frac{4.\left(x+1\right).\left(x^3-4x\right)}{4.\left(x+1\right)}\)
\(=x^3-4x\)
\(\left(x^4-2x^3+2x-1\right):\left(x^2-1\right)\)
\(=\left(x^4-2x^3+x^2-x^2+2x-1\right):\left(x^2-1\right)\)
\(=[x^2.\left(x^2-2x+1\right)-\left(x^2-2x+1\right)]:\left(x^2-1\right)\)
\(=\left(x^2-1\right).\left(x^2-2x+1\right):\left(x^2-1\right)\)
\(=x^2-2x+1\)
\(=\left(x-1\right)^2\)
Câu 1:
a) (-4xy)(2xy-3xy2+5)
= -8x2y2+12x2y3-20xy
b) (2x-3)(6xy-5x2y+2)
= 12x2y-10x3y+4x-18xy+15x2y-6
=28x2y-10x3y-18xy+4x-6
Câu 2:
a) x2+2x+1 = (x+1)2
b) 4x2-9y2 = (2x+3y)(2x-3y)
c) 2x+4y-x-2y = x+2y
Câu 3:
tại x,y bằng bao nhiêu chưa cho biết nên câu 3 bỏ qua
HOK TỐT~
A = -x2 + 2x + 7 = -( x2 - 2x + 1 ) + 8 = -( x - 1 )2 + 8 ≤ 8 ∀ x
Dấu "=" xảy ra <=> x = 1 => MinA = 8
B = 5x - 3x2 + 6 = -3( x2 - 5/3x + 25/36 ) + 97/12 = -3( x - 5/6 )2 + 97/12 ≤ 97/12 ∀ x
Dấu "=" xảy ra <=> x = 5/6 => MinB = 97/12
\(4x^2-4x-3\)
\(=4x^2-2x+6x-3\)
\(=2x.\left(x-1\right)+3.\left(x-1\right)\)
\(=\left(2x+3\right).\left(x-1\right)\)
\(x^2-4x+3\)
\(=x^2-3x-x+3\)
\(=\left(x^2-x\right)-\left(3x-3\right)\)
\(=x.\left(x-1\right)-3.\left(x-1\right)\)
\(=\left(x-3\right).\left(x-1\right)\)
\(x^4-8x+63\)
\(=x^4+4x^3+9x^2-4x^3-16x^2-36x+7x^2+28x+63\)
\(=\left(x^4+4x^3+9x^2\right)-\left(4x^3+16x^2+36x\right)+\left(7x^2+28x+63\right)\)
\(=x^2.\left(x^2+4x+9\right)-4x.\left(x^2+4x+9\right)+7.\left(x^2+4x+9\right)\)
\(=\left(x^2-4x+7\right).\left(x^2+4x+9\right)\)