Question

rezolvati in multimea numerelor naturale inecuatiile a) 0,8x+2,97>1,5la patrat x3,8
b)7,02+0,6x mai mare sau egal 3,6 x 2,5la patrat
c)5,43-1,2x < 0,4 x 1,5la patrat
d)9,27-1,8xmai mare sau egal 2,4la patart x 0,5   URGENT

Answer 1

[tex]\it0,8 x + 2,97 \ \textgreater \ 1,5^2\cdot3,8 |_{\cdot 100} \Rightarrow 80x+297 \ \textgreater \ 2,25\cdot380 \\\;\\ \Rightarrow \it 80x +297 \ \textgreater \ 855 \Rightarrow 80x \ \textgreater \ 855-297 \Rightarrow 80x \ \textgreater \ 558 \\\;\\ \Rightarrow\it x\ \textgreater \ 558:80 \Rightarrow x\ \textgreater \ \dfrac{\ \ 558^{(2}}{80} \Rightarrow x\ \textgreater \ \dfrac{^{25)}279}{\ \ 40} \\\;\\ \Rightarrow \it x\ \textgreater \ \dfrac{6975}{1000} \Rightarrow x \ \textgreater \ 6, 975\ \ .[/tex]

Deoarece x  este număr natural, vom obţine :
 
x ∈ {7, 8, 9, ...} sau x ∈ ℕ - {0, 1, 2, 3, 4, 5, 6}