Ta có: 

\(S=3.2^0-3^1+3.2^1-3^2+3.2^2+3.2^3-3^3+3.2^4-3^4+...-3^7+3.2^{10}+3.2^{11}-3^8+3.2^{12}\)

\(=3.\left(2^0+2^1+2^2+2^3+2^4+...+2^{10}+2^{11}+2^{12}\right)-\left(3^1+3^2+3^3+...+3^7+3^8\right)\)

Đặt: \(A=2^0+2^1+2^2+...+2^{11}+2^{12}\)

=> \(2.A=2^1+2^2+2^3+...+2^{12}+2^{13}\)

=> \(2.A-A=2^{13}-2^0\)

\(\Rightarrow A=2^{13}-1=8191\)

Đặt: \(B=3^1+3^2+3^3+...+3^8\)

 \(\Rightarrow3.B=3^2+3^3+3^4+...+3^9\)

=> \(3B-B=3^9-3^1=19680\)

=> \(2B=19680\Rightarrow B=9840\)

=> S=3.A-B=3.8191-9840=14733

a) \(L=4-8+12-16+20-24+...+220-224\)

\(\Rightarrow L=\left(-4\right)+\left(-4\right)+\left(-4\right)+...+\left(-4\right)\) (có 28 số -4)

\(\Rightarrow L=\left(-4\right).28=-112\)

c) \(O=6-12+18-24+30-36+354-360\) 

\(\Rightarrow O=\left(-6\right)+\left(-6\right)+\left(-6\right)+...+\left(-6\right)\) (có 30 số -6)

\(\Rightarrow O=\left(-6\right).30=-180\)

e) \(P=3-6+9-12+15-18+...+147-150\)

\(\Rightarrow P=\left(-3\right)+\left(-3\right)+\left(-3\right)+...+\left(-3\right)\) (có 25 số -3)

\(\Rightarrow P=\left(-3\right).25=-75\)

b)

S = 3 + 5 - 7 - 9 + 11 + 13 - 15 - 17 + ... + 243 + 245 - 247 - 249

S = (3 - 7) + (5 - 9) + ... + (243 - 247) + (245 - 249)

S = (-4) + (-4) + ... + (-4) + (-4)

Tổng trên có số số hạng là : [(249 - 3) : 2 + 1] : 2 = 62 (số hạng)

Suy ra S = (-4) x 62 = -248

d)

E = 2 - 4 + 6 - 8 + ... + 218 - 220

E = (2 - 4) + (6 - 8) + ... + (218 - 220)

E = (-2) + (-2) + ... + (-2)

Tổng trên có số số hạng là: [(220 - 2) : 2 + 1] : 2 = 55 (số hạng)

Suy ra E = (-2) x 55 = -110

(24 + 6 x 5 + 6 ) – (12 + 6 x 3)

= (6 x 4 + 6 x 5 + 6 x 1) – (6 x 2 + 6 x 3)

= 6 x (4 + 5 + 1) – 6 x (2 + 3)

= 6 x 10 – 6 x 5

= 6 x (10 – 5)

= 6 x 5

= 30

56/7*2 = 4
12*3+6 = 42
27/ 3/ 3= 3
2*6/2 = 6
24/3/2 = 4

\(E=\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{8}+\dfrac{1}{2}+\dfrac{1}{12}\)

\(E=\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\left(\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{1}{8}+\dfrac{1}{12}+\dfrac{1}{24}\right)\)

\(E=\dfrac{2}{2}+\dfrac{3}{6}+\left(\dfrac{1}{8}+\dfrac{3}{24}\right)\)

\(E=1+\dfrac{1}{2}+\left(\dfrac{1}{8}+\dfrac{1}{8}\right)\)

\(E=\left(\dfrac{2}{2}+\dfrac{1}{2}\right)+\dfrac{2}{8}\)

\(E=\dfrac{3}{2}+\dfrac{1}{4}\)

\(E=\dfrac{6}{4}+\dfrac{1}{4}\)

\(E=\dfrac{7}{4}\)

a: k=3

y=2x