thực hiện phép tính thực hiện phép tính (x+1)^2+(x-1)^2
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1, = 1/8 : 1/6 = 3/4
2, = 5/4 + 1/4 = 3/2
3, = 5/12 + 1/12= 1/2
4, còn số phần là:
1 - ( 3/7 + 2/5) = 6/35 ( phần bể chưa có nước)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: \(\left(x-2\right)^3-x\left(x-1\right)\left(x+1\right)+6x\left(x-3\right)\)
\(=x^3-6x^2+12x-8-x\left(x^2-1\right)+6x^2-18x\)
\(=x^3-6x-8-x^3+x\)
\(=-5x-8\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
x + 2 x - 1 = x x - 1 + 2 x - 1 = x 2 - x + 2 x - 2 = x 2 + x - 2
Chọn C x 2 + x - 2
![](https://rs.olm.vn/images/avt/0.png?1311)
\(1.\)
\(\left|-0,75\right|+\frac{1}{4}-2\frac{1}{2}\)
\(=0,75+\frac{1}{4}-\frac{5}{2}\)
\(=\frac{3}{4}+\frac{1}{4}-\frac{10}{4}\)
\(=\frac{4}{4}-\frac{10}{4}\)
\(=\frac{-6}{4}=\frac{-3}{2}\)
\(2.\)
\(a,3\frac{1}{2}-\frac{1}{2}x=\frac{2}{3}\)
\(\frac{7}{2}-\frac{1}{2}x=\frac{2}{3}\)
\(\frac{1}{2}x=\frac{7}{2}-\frac{2}{3}\)
\(\frac{1}{2}x=\frac{17}{6}\)
\(x=\frac{17}{6}:\frac{1}{2}\)
\(x=\frac{17}{3}\)
Vậy x = \(\frac{17}{3}\)
\(b,3,2x+\left(-1,2\right)x+2,7\)\(=-4,9\)
\(x\cdot\left[3,2++\left(-1,2\right)\right]+2,7=-4,9\)
\(x\cdot2+2,7=-4,9\)
\(x\cdot2=-4,9-2,7\)
\(x\cdot2=-7,6\)
\(x=-7,6:2\)
\(x=-3,8\)
Vậy x=-3,8
\(3.\)
\(Có:y=f\left(x\right)\)\(=2x+\frac{1}{2}\)
\(\Rightarrow f\left(0\right)=2\cdot0+\frac{1}{2}\)\(=0+\frac{1}{2}=\frac{1}{2}\)
\(\Rightarrow f\left(1\right)=2\cdot1+\frac{1}{2}=2+\frac{1}{2}=\frac{4}{2}+\frac{1}{2}=\frac{5}{2}\)
\(\Rightarrow f\left(\frac{1}{2}\right)=2\cdot\frac{1}{2}+\frac{1}{2}\)\(=\frac{2}{2}+\frac{1}{2}=\frac{3}{2}\)
\(\Rightarrow f\left(-2\right)=2\cdot\left(-2\right)+\frac{1}{2}=-4+\frac{1}{2}=\frac{-8}{2}+\frac{1}{2}=\frac{-7}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a.\left(x^2-3x+2\right)\left(x-2\right)\)
\(=x^3-2x^2-3x^2+6x+2x-4\)
\(=x^3-5x^2+8x-4\)
b. Từ kết quả ở câu a, ta có:
\(\left(x^2-3x+2\right)\left(x-2\right)\)
\(=\left(-x^2-3\left(-x\right)+2\right)\left(2-\left(-x\right)\right)\) (ta thay x bằng -x nha)
\(=\left(-x^2+3x+2\right)\left(2+x\right)\)
\(=-2x^2-x^3+6x+3x^2+2+2x\)
\(=-x^3+x^2+8x+2\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: (x^2-3x+2)(x-2)
=x^3-2x^2-3x^2+6x+2x-4
=x^3-5x^2+8x-4
b: (x^2-3x+2)(2-x)
=-(x-2)(x^2-3x+2)
=-(x^3-5x^2+8x-4)
=-x^3+5x^2-8x+4
`(x+1)^2 + (x-1)^2`
`= x^2 + 2x + 1 + x^2 - 2x + 1`
`= 2x^2 + 2`
`= 2(x^2 +1)`
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Áp dụng hằng đẳng thức:
\(\left(a\pm b\right)^2=a^2\pm2ab+b^2\)