b: \(\Leftrightarrow x-15-27-x+x-13=-1\)

\(\Leftrightarrow x-55=-1\)

hay x=54

nhầm (x-16/667)

\(\dfrac{3+\dfrac{3}{7}-\dfrac{3}{11}+\dfrac{3}{1001}-\dfrac{3}{13}}{\dfrac{9}{1001}-\dfrac{9}{13}+\dfrac{9}{7}-\dfrac{9}{11}+9}\\ =\dfrac{3\left(1+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{1001}-\dfrac{1}{13}\right)}{9\left(1+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{1001}-\dfrac{1}{13}\right)}\\ =\dfrac{3}{9}\\ =\dfrac{1}{3}\)

Ta có:\(1001=1000+1=x+1\)

\(x^8-1001x^7+1001x^6+...+1001x^2-1001x+250\\ =x^8-\left(x+1\right)x^7+\left(x+1\right)x^6+...+\left(x+1\right)x^2-\left(x+1\right)x\\ =x^8-x^8-x^7+x^7+x^6+...+x^3+x^2-x^2-x+250\\ =-x+250=-1000+250\\ =-750\)

1. \(x:\left(1001:13\right)=29\)

\(\Leftrightarrow x:77=29\)

\(\Leftrightarrow x=2233\)

2. \(x:\left(15\cdot17\right)=8\)

\(\Leftrightarrow x:255=8\)

\(\Leftrightarrow x=2040\)

P/s: Có thế tính sai :<

x:(1001:13)=29

x:77=29

x=29x77=2233

x:(15x17)=8

x:225=8

x=225x8=2040

\(a)x:(1001:13)=29\)

\(\Rightarrow x:77=29\)

\(\Rightarrow x=29\times77=2233\)

\(b)x:(15\times17)=8\)

\(\Rightarrow x:255=8\)

\(\Rightarrow x=8\times255=2040\)

oa

a) Câu hỏi của Hinamori Amu - Toán lớp 7 | Học trực tuyến

a,+b,:Câu hỏi của Hinamori Amu - Toán lớp 7 | Học trực tuyến

a) M=\(x^3+x^2y-xy^2-y^3+x^2-y^2+2x+2y+3\)

=\(x^2\left(x+y+1\right)-y^2\left(x+y+1\right)+2\left(x+y+1\right)+1\)

=\(x^2.0-y^2.0+2.0+1=1\)

Vậy với x+y+1=0 thì M=1

b) hình như thiếu đề

A,\(\left(\left(1002-998\right):2+1\right)\cdot\left(998+1002\right):2\)

\(=5000\)

B,\(\left(\frac{13}{5}+\frac{2}{5}\right)-\left(\frac{9}{8}+\frac{7}{8}\right)=3-2=1\)

A/  \(998+999+1000+1001+1002\)

\(=\left(998+1002\right)+\left(999+1001\right)+1000\)

\(=2000+2000+1000\)

\(=5000\)

B/  \(\frac{13}{5}-\frac{9}{8}+\frac{2}{5}-\frac{7}{8}\)

\(=\left(\frac{13}{5}+\frac{2}{5}\right)-\left(\frac{9}{8}+\frac{7}{8}\right)\)

\(=\frac{15}{5}-\frac{16}{8}\)

\(=3-2=1\)

bó tay luôn