Question

Afla necunoscuta 4x+(x+1)+(x+2)+......+(x+10)+120=203

Answer 1

Răspuns:

x = 2

Explicație pas cu pas:

4x+(x+1)+(x+2)+......+(x+10)+120=203 <=>

4x + 10x + (1+2+3+...+10) = 203 -120 <=>

14x + 11·10:2 = 83  <=>

14x + 55 = 83  <=>

14x = 83-55 <=>

14x = 28 =>

x = 28:14  => x = 2

Answer 2

$\it 4x+(x+1)+(x+2)+(x+3)+\ ...\ +(x+10)+120=203|_{-120}\ \Rightarrow\\ \\ \\\Rightarrow4x+\underbrace{x+x+x+\ ...\ +x}_{10\ termeni}+1+2+3+\ ...\ +10=83\ \Rightarrow\\ \\ \\ \Rightarrow14x+\dfrac{10\cdot11}{2}=83 \Rightarrow\ 14x+55=83|_{-55}\ \Rightarrow 14x=28|_{:14}\ \Rightarrow\ x=2$