1)
30-30:3=30-10=20
2.
1 caiet =40:10=4 l3i
5 caiete= 5×4=20 lei
3.
B={1,3,5}
A={1,2,3,4}
B={1,3,5}
A∪B={1,2,3,4,5}
4.
(12+8)/2=20/2=10
5
v=10×5×4=20×10=200 cm³
6.
(1+3+5):3=9:3=3
II. Subiectul 5
[tex]E(x)=( \frac{x+1}{x-3}- \frac{2x^{2} +3x-3}{ x^{2} -9}+
\frac{2x-1}{x+3}):( \frac{2x^{2}-18}{ x^{2} +6x+9} \\ \\
\frac{(x+1)(x+3)-(2 x^{2} +3x-3)+(2x-1)(x-3)}{ x^{2} -9} :(
\frac{2(x^{2}-9)}{ x^{2} +3x+3x+9}) \\ \\ \frac{ x^{2} +3x+x+3-2 x^{2}
-3x+3+(2 x^{2} -6x-x+3)}{(x-3)(x+3)} :\frac{2(x^{2}-9)}{ (x+3) ^{2}}
\\ \\ \frac{ x^{2}-6x+9}{(x-3)(x+3)} \cdot
\frac{(x+3)(x+3)}{2(x+3)(x-3)} = \\ \\ \frac{ (x-3)^{2} }{(x-3)} \cdot
\frac{1}{2(x-3)} = \\ \\E(x)= \frac{1}{2}
[/tex]
II.
2.
[tex]2^{n+3}-2^{n+2}+7\cdot2^{n+1}-2^{n} :17 \\ \\ 2^{n}\cdot2^{3} -2^{n}\cdot 2^{2} }+7\cdot2^{n}\cdot2}-2^{n} = \\ \\ 2^{n}( 2^{3}- 2^{2}+7\cdot2-1)} = \\ \\ 2^{n}(8-4+14-1)=2^{n}\cdot17 \\ \\ 2^{n+3}-2^{n+2}+7\cdot2^{n+1}-2^{n}=2^{n}\cdot17 [/tex]
este divizibil cu 17!!!
