3. [tex]a=( \sqrt{2}+ \sqrt{50}- \sqrt{72})* \sqrt{5}- \frac{16}{21}:(- \frac{2}{63} ) [/tex]
[tex]a=( \sqrt{2}+5 \sqrt{2}-6 \sqrt{2})* \sqrt{5}+ \frac{16}{21}* \frac{63}{2} [/tex]
[tex]a=0 \sqrt{5}+8*3 [/tex]
a=0+24
a=24
4. |2x-1|≤3
2x-1≤3, 2x-1≥0
-(2x-1)≤3, 2x-1<0
x≤2, [tex]x \geq \frac{1}{2} [/tex]
x≥-1, [tex]x\ \textless \ \frac{1}{2} [/tex]
x∈[tex][ \frac{1}{2} ,2][/tex]
x∈[tex][-1, \frac{1}{2}) [/tex]
x∈[-1, 2]
5. E(x)=(x+1)²+2(x²+4x+3)+(x+3)²=(x+1+x+3)²=(2x+4)²=(2(x+2))²
