rút gọn
a) x^7 - 2x^3 / 2x^4 - x^3
b) (x+2)^2 - (x-2)^2 / 16x
c) 24,5x^2 - 0,5y^2 / 3,5x^2 - 0,5xy
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Những câu hỏi liên quan
6 tháng 7 2016
a) \(3x^2-2x\left(5+1,5x\right)+10x\)
\(=3x^2-10x-3x^2+10x=0\)
b) \(7x\left(4y-x\right)+4y\left(y-7x\right)-2\left(2y^2-3,5x\right)\)
\(=28xy-7x^2+4y^2-28xy-4y^2+7x\)
\(=-7x^2+7x\)
TN
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NN
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AH
Akai Haruma
Giáo viên
30 tháng 6
Lời giải:
a.
$(2x+3)^2-4(x-2)(x+2)=(4x^2+12x+9)-4(x^2-4)$
$=4x^2+12x+9-4x^2+16=12x+25$
b.
$(4x^3-16x^2+17x-5):(2x-5)$
$=[2x^2(2x-5)-3x(2x-5)+(2x-5)]:(2x-5)$
$=(2x-5)(2x^2-3x+1):(2x-5)=2x^2-3x+1$
12 tháng 7 2019
\(a,\left(6x+1\right)\left(x+2\right)-2x\left(3x-5\right)\)
\(=6x^2+12x+x+2-6x^2+10x\)
\(=23x+2\)
12 tháng 7 2019
a) (6x + 1)(x + 2) - 2x(3x - 5)
= 6x2 + 12x + x + 2 - 6x2 + 10x
= (6x2 - 6x2) + (12x + x + 10x) + 2
= 23x + 2
b) (2x - 1)2 - (2x - 3)(2x + 3)
= 4x2 - 4x + 1 - 4x2 + 9
= (4x2 - 4x2) - 4x + (1 + 9)
= -4x + 10
c) (2x - 3)3 - (3x + 1)(5 - 4x) - 16x2
= 8x3 - 36x2 + 54x - 15x + 12x2 - 5 + 4x - 16x2
= 8x3 - (36x2 - 12x2 + 16x2) + (54x - 15x + 4x) - 5
= 8x3 - 40x2 + 43x - 5
d) (3x + 2) - (x - 5) - x(3x - 13)
= 3x + 2 - x + 5 - 3x2 + 13x
= (3x - x + 13x) + (2 + 5) - 3x2
= 15x + 7 - 3x2
22 tháng 10 2023
1:
a: \(\left(2x-5\right)^2-4x\left(x+3\right)\)
\(=4x^2-20x+25-4x^2-12x\)
=-32x+25
b: \(\left(x-2\right)^3-6\left(x+4\right)\left(x-4\right)-\left(x-2\right)\left(x^2+2x+4\right)\)
\(=x^3-6x^2+12x-8-\left(x^3-8\right)-6\left(x^2-16\right)\)
\(=-6x^2+12x-6x^2+96=-12x^2+12x+96\)
c: \(\left(x-1\right)^2-2\left(x-1\right)\left(x+2\right)+\left(x+2\right)^2+5\left(2x-3\right)\)
\(=\left(x-1-x-2\right)^2+5\left(2x-3\right)\)
\(=\left(-3\right)^2+5\left(2x-3\right)\)
\(=9+10x-15=10x-6\)
2:
a: \(\left(2-3x\right)^2-5x\left(x-4\right)+4\left(x-1\right)\)
\(=9x^2-12x+4-5x^2+20x+4x-4\)
\(=4x^2+12x\)
b: \(\left(3-x\right)\left(x^2+3x+9\right)+\left(x-3\right)^3\)
\(=27-x^3+x^3-9x^2+27x-27\)
\(=-9x^2+27x\)
c: \(\left(x-4\right)^2\left(x+4\right)-\left(x-4\right)\left(x+4\right)^2+3\left(x^2-16\right)\)
\(=\left(x-4\right)\left(x+4\right)\left(x-4-x-4\right)+3\left(x^2-16\right)\)
\(=\left(x^2-16\right)\left(-8\right)+3\left(x^2-16\right)\)
\(=-5\left(x^2-16\right)=-5x^2+80\)
\(a,\dfrac{x^7-2x^3}{2x^4-x^3}=\dfrac{x^3\left(x^4-2\right)}{x^3\left(2x-1\right)}=\dfrac{x^4-2}{2x-1}\)
\(b,\dfrac{\left(x+2\right)^2-\left(x-2\right)^2}{16x}=\dfrac{\left(x+2-x+2\right)\left(x+2+x-2\right)}{16x}=\dfrac{4.2x}{16x}=\dfrac{1}{2}\)
\(c,\dfrac{24,5x^2-0,5y^2}{3,5x^2-0,5y^2}=\dfrac{0,5\left(49x^2-y^2\right)}{0,5\left(7x^2-y^2\right)}=\dfrac{49x^2-y^2}{7x^2-y^2}\)
a) \(\dfrac{x^7-2x^3}{2x^4-x^3}=\dfrac{x^3\left(x^4-2\right)}{x^3\left(2x-1\right)}=\dfrac{x^4-2}{2x-1}\)
b)\(\dfrac{\left(x+2\right)^2-\left(x-2\right)^2}{16x}=\dfrac{x^2+4x+4-\left(x^2-4x+4\right)}{16x}\)=\(\dfrac{x^2+4x+4-x^2+4x-4}{16x}=\dfrac{8x}{16x}=\dfrac{1}{2}\)