Ta có \(A\left(\frac{1}{2}\right)=\frac{1}{2}+\left(\frac{1}{2}\right)^2+\left(\frac{1}{2}\right)^3+...+\left(\frac{1}{2}\right)^{100}=\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\)

=> \(2.A\left(\frac{1}{2}\right)=1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\)

=> \(2A\left(\frac{1}{2}\right)-A\left(\frac{1}{2}\right)=\left(1+\frac{1}{2}+\frac{1}{2^2}+...+\frac{1}{2^{99}}\right)-\left(\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+...+\frac{1}{2^{100}}\right)\)

=> \(A\left(\frac{1}{2}\right)=1-\frac{1}{2^{100}}\)

a)\(f\left(x\right)=5+3x^2-x-2x^2\)

\(f\left(x\right)=x^2-x+5\)

\(g\left(x\right)=3x+3-x-x^2\)

\(g\left(x\right)=-x^2+2x+3\)

b)\(f\left(x\right)+g\left(x\right)=x^2-x+5-x^2+2x+3\)

\(f\left(x\right)+g\left(x\right)=x+8\)

c) \(f\left(x\right)-H\left(x\right)=g\left(x\right)\)

\(\Leftrightarrow H\left(x\right)=f\left(x\right)-g\left(x\right)\)

\(\Rightarrow H\left(x\right)=x^2-x+5-\left(-x^2+2x+3\right)\)

\(\Leftrightarrow H\left(x\right)=x^2-x+5+x^2-2x-3\)

\(\Leftrightarrow H\left(x\right)=2x^2-3x+2\)

#H

phần c thui nha mấy bn

Đáp án: 

Gọi số cần tìm là abc

Ta có: cba  = abc + 792

cx100 + bx10 + a = ax +100 + bx10 + c + 792

cx99 = a x 99+ 792

c = a+ (792 : 99) = a + 8

Đáp án: 

Gọi số cần tìm là abc

Ta có: cba  = abc + 792

cx100 + bx10 + a = ax +100 + bx10 + c + 792

cx99 = a x 99+ 792

c = a+ (792 : 99) = a + 8

1. = 5

2. = 8

k cho tui he