Question

Am nevoie de ajutor. REPEDE VĂ ROG!!!

Answer 1

a) 1+2+3+4+...+121=121×122÷2=7381

b) 31+32+...+150= 1+2+...+150 -(1+2+3+...+30)= 150×151÷2 - 30×31÷2= 10860

c) 2+4+6+...+108= 2×(1+2+...+54)=2×54×55÷2=2970

d) 1+3+...+109= 1+2+3+....+109 - (2+4+...+108) = 109×110÷2 - 2970= 3025

e) 3+7+11+...+43= 3×11 + 4×(1+2+...+10)= 33+ 4×10×11÷2= 253

f) 9+14+19+...+109= 9×21 + 5×(1+2+...+20)= 189 +5×20×21÷2= 1239

a)

${2}^{n} \times ( {2}^{2} + 2 + 1) = 7 \times {2}^{102} = > 7 \times {2}^{n} = 7 \times {2}^{102} = > n = 102$

b)

${3}^{n} \times ( {3}^{2} + 3 + 1) = 13 \times 27 = > {3}^{n} \times 13 = 13 \times 27 = > {3}^{ n} = 27 = > n = 3$