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12 tháng 12 2023
a: (x+1)(3-x)(x-2)2
\(=\left(3x-x^2+3-x\right)\left(x^2-4x+4\right)\)
\(=\left(-x^2+2x+3\right)\left(x^2-4x+4\right)\)
\(=-x^4+4x^3-4x^2+2x^3-8x^2+8x+3x^2-12x+12\)
\(=-x^4+6x^3-9x^2-4x+12\)
b: \(9x\left(1-x\right)+\left(3x-2\right)\left(3x+2\right)\)
\(=9x-9x^2+\left(3x\right)^2-4\)
\(=9x-9x^2+9x^2-4=9x-4\)
10 tháng 7 2021
a) Ta có: \(A=\left(7-2x\right)\left(7+2x\right)+\left(2x+7\right)^2\)
\(=7-4x^2+4x^2+28x+49\)
\(=28x+56\)
b) Ta có: \(B=\left(4x-5\right)^2-\left(2x-1\right)\left(8x-5\right)\)
\(=16x^2-40x+25-\left(16x^2-10x-8x+5\right)\)
\(=16x^2-40x+25-16x^2+18x-5\)
\(=-22x+20\)
c) Ta có: \(C=\left(5x-3\right)^2-2\left(5x-3\right)\left(5-5x\right)+\left(5x-5\right)^2\)
\(=\left(5x-3\right)^2+2\cdot\left(5x-3\right)\left(5x-5\right)+\left(5x-5\right)^2\)
\(=\left(5x-3+5x-5\right)^2\)
\(=\left(10x-8\right)^2\)
\(=100x^2-160x+64\)
d) Ta có: \(D=\left(2a+3b-c\right)\left(2a-3b+c\right)-\left(4a^2-9b^2-c^2\right)\)
\(=\left[\left(2a+\left(3b-c\right)\right)\left(2a-\left(3b-c\right)\right)\right]-\left(4a^2-9b^2-c^2\right)\)
\(=4a^2-\left(3b-c\right)^2-4a^2+9b^2+c^2\)
\(=-9b^2+6bc-c^2+9b^2+c^2\)
=6bc
8 tháng 9 2023
2:
a: =>x^2+3x-4x-12-(x^2-5x+x-5)=8
=>x^2-x-12-x^2+4x+5=8
=>3x-7=8
=>3x=15
=>x=5
b: =>3x^2+3x-2x-2-3x^2-21x=13
=>-20x=15
=>x=-3/4
c: =>x^2-25-x^2-2x=9
=>-2x=25+9=34
=>x=-17
d: =>x^3-1-x^3+3x=1
=>3x-1=1
=>3x=2
=>x=2/3
5 tháng 10 2021
\(A=5x^2-3x-x^3+x^2+x^3-62x-10+3x\\ A=6x^2-62x-10\\ B=x^3+x^2+x-x^3-x^2-x+5=5\\ C=3x^2y-15xy^2+15xy^2-10y^3+10y^2-3x^2y-4=-4\)
5 tháng 10 2021
b: Ta có: \(B=x\left(x^2+x+1\right)-x^2\left(x+1\right)-x+5\)
\(=x^3+x^2+x-x^3-x^2-x+5\)
=5
20 tháng 12 2022
a: \(=\dfrac{x^2-x+x+1+2x}{\left(x-1\right)\left(x+1\right)}=\dfrac{\left(x+1\right)^2}{\left(x-1\right)\left(x+1\right)}=\dfrac{x+1}{x-1}\)
b: \(=\dfrac{x^2+2x-4x-2x+4}{\left(x-2\right)\left(x+2\right)}=\dfrac{x^2-4x+4}{\left(x-2\right)\left(x+2\right)}=\dfrac{x-2}{x+2}\)
c: \(=\dfrac{2x^2-3x-9-x^2+3x+x^2+6x+9}{\left(x-3\right)\left(x+3\right)}\)
\(=\dfrac{2x^2+6x}{\left(x-3\right)\left(x+3\right)}=\dfrac{2x}{x-3}\)
SS
2
H9
HT.Phong (9A5)
CTVHS
16 tháng 7 2023
a) \(\left(x+3\right)^2+\left(x-3\right)^2+2\left(x^2+9\right)\)
\(=\left(x+3\right)^2+2\left(x+3\right)\left(x-3\right)+\left(x-3\right)^2\)
\(=\left[\left(x+3\right)+\left(x-3\right)\right]^2\)
\(=\left(x+3+x-3\right)^2\)
\(=\left(2x\right)^2\)
\(=4x^2\)
b) \(\left(4x-1\right)^3-\left(4x-3\right)\left(16x^2+3\right)\)
\(=\left(64x^3-48x^2+12x-1\right)-\left(64x^3+12x-48x^2-9\right)\)
\(=64x^3-48x^2+12x-1-64x^3-12x+48x^2+9\)
\(=\left(64x^3-64x^3\right)-\left(48x^2-48x^2\right)+\left(12x-12x\right)-\left(1-9\right)\)
\(=0-0+0+8\)
\(=8\)
KV
16 tháng 7 2023
a) (x + 3)² + (x - 3)² + 2(x² - 9)
= (x + 3)² + 2(x + 3)(x - 3) + (x - 3)²
= (x + 3 + x - 3)²
= (2x)²
= 4x²
b) (4x - 1)³ - (4x - 3)(16x² + 3)
= 64x³ - 48x² + 12x - 1 - 64x³ - 12x + 48x² + 9
= (64x³ - 64x³) + (-48x² + 48x²) + (12x - 12x) + (-1 + 9)
= 8
17 tháng 10 2021
a: \(\left(2x-1\right)^2-3\left(x-1\right)\left(x+2\right)-\left(x-3\right)^2\)
\(=4x^2-4x+1-x^2+6x-9-3\left(x^2+x-2\right)\)
\(=3x^2+2x-8-3x^2-3x+6\)
=-x+2
b: \(\left(x-2\right)\left(2x-1\right)-3\left(x+1\right)^2-4x\left(x+2\right)\)
\(=2x^2-x-4x+2-3x^2-6x-3-4x^2-8x\)
\(=-5x^2-19x-1\)
a) \(\left(2x+1\right)^2-\left(3-x\right)^2\)
\(=4x^2+4x+1-9+6x-x^2\)
\(=3x^2+10x+\left(1-9\right)=3x^2+10x-8\)
\(b,\left(x-2\right)^3-\left(5+x\right)^3\)
\(=\left(x-2-5-x\right)\left[\left(x+2\right)^2+\left(x+2\right)\left(5+x\right)+\left(5+x\right)^2\right]\)
\(=-3\left(x+2\right)^2+\left(x+2\right)\left(5+x\right)\left(5+x\right)^2\)