Rút gọn
\(\frac{1+2^2+2^4+.............+2^{22}}{2^4+2^8+............+2^{24}}\)
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\(\frac{1+2^4+2^8+.....+2^{20}}{2^4+2^8+.......+2^{24}}=\frac{1+2^4+2^8+....+2^{20}}{2^4\cdot\left(1+2^4+2^8+...+2^{20}\right)}\)
\(=\frac{1}{2^4}=\frac{1}{16}\)
Ta nhận thấy mẫu của biểu thức trên là:
x26+x24+x22+...+x2+1=(x26+x22+...+x2)+(x24+x20+...+x4+1)
=x2(x24+x20+...+x16+...+1)+(x24+x20+...+x4+1)
=(x24+x20+...+1)(x2+1)
Như vậy\(\frac{x^{24}+x^{20}+x^{16}+...+1}{\left(x^{24}+x^{20}+...+1\right)\left(x^2+1\right)}\)=\(\frac{1}{x^2+1}\)
Ta có: \(\dfrac{x^{24}+x^{20}+x^{16}+...+x^4+1}{x^{26}+x^{24}+x^{22}+...+x^2+1}\)
\(=\dfrac{x^{24}+x^{20}+x^{16}+...+x^4+1}{\left(x^{26}+x^{22}+...+x^2\right)+\left(x^{24}+x^{20}+x^{16}+...+x^4+1\right)}\)
\(=\dfrac{x^{24}+x^{20}+x^{16}+...+x^4+1}{x^2\left(x^{24}+x^{20}+...+1\right)+\left(x^{24}+x^{20}+x^{16}+...+x^4+1\right)}\)
\(=\dfrac{x^{24}+x^{20}+x^{16}+...+x^4+1}{\left(x^{24}+x^{20}+x^{16}+...+1\right)\left(x^2+1\right)}\)
\(=\dfrac{1}{x^2+1}\)
x24+x20+x16+...+x4+1x26+x24+x22+...+x2+1x24+x20+x16+...+x4+1x26+x24+x22+...+x2+1
=x24+x20+x16+...+x4+1(x26+x22+...+x2)+(x24+x20+x16+...+x4+1)=x24+x20+x16+...+x4+1(x26+x22+...+x2)+(x24+x20+x16+...+x4+1)
=x24+x20+x16+...+x4+1x2(x24+x20+...+1)+(x24+x20+x16+...+x4+1)=x24+x20+x16+...+x4+1x2(x24+x20+...+1)+(x24+x20+x16+...+x4+1)
=x24+x20+x16+...+x4+1(x24+x20+x16+...+1)(x2+1)
1. 10 phần 14 = 5/7
2. 5 phần 15 = 1/3
3. 14 phần 22 = 7/11
4. 2 phần 8 = 1/4
5. 4 phần 24= 1/6
6. 2 phần 10 = 1/5
1. \(\frac{10}{14}=\frac{10:2}{14:2}=\frac{5}{7}\)
2. \(\frac{5}{15}=\frac{5:5}{15:5}=\frac{1}{3}\)
3. \(\frac{14}{22}=\frac{14:2}{22:2}=\frac{7}{11}\)
4. \(\frac{2}{8}=\frac{2:2}{8:2}=\frac{1}{4}\)
5. \(\frac{4}{24}=\frac{4:4}{24:4}=\frac{1}{6}\)
6. \(\frac{2}{10}=\frac{2:2}{10:2}=\frac{1}{5}\)
b: \(=\left(x^2+3x+1-3x+1\right)^2=\left(x^2+2\right)^2\)
1) Ta có: \(\left(x+2\right)^2+\left(x-3\right)^2\)
\(=x^2+4x+4+x^2-6x+9\)
\(=2x^2-2x+13\)
2) Ta có: \(\left(4-x\right)^2-\left(x-3\right)^2\)
\(=\left(4-x-x+3\right)\left(4-x+x-3\right)\)
\(=-2x+7\)
3) Ta có: \(\left(x-5\right)\left(x+5\right)-\left(x+5\right)^2\)
\(=x^2-25-x^2-10x-25\)
=-10x-50
4) Ta có: \(\left(x-3\right)^2-\left(x-4\right)\left(x+4\right)\)
\(=x^2-6x+9-x^2+16\)
=-6x+25
5) Ta có: \(\left(y^2-6y+9\right)-\left(y-3\right)^2\)
\(=y^2-6y+9-y^2+6y-9\)
=0
6) Ta có: \(\left(2x+3\right)^2-\left(2x-3\right)\left(2x+3\right)\)
\(=4x^2+12x+9-4x^2+9\)
=12x+18
Bạn xem lại đề bài đi mk thấy sai sai hay sao í