A construction worker bought \( 21 \frac{1}{4} \) pounds of nails. When those nails were all used, he bought \( 1 \frac{1}{2} \) times as many nails as he had bought the first time. How many pounds of nails did he buy the second time?

Find \( \|\mathbf{v}\| \). \( \mathbf{v}=-3 \mathbf{i}+7 \mathbf{j} \) \( \begin{array}{l}\|\mathbf{v}\|=\square \\ \text { (Simplify your answer. Type an exact answer, using radicals as needed.) }\end{array} \)

257. Funksiýalaryň grafigini guruň: \( \begin{array}{ll}\text { a) } y=x^{2}+6 x ; & \text { ç) } y=0,5 x^{2}-4\end{array} \)

7. Исследуйте но чётность и нечетность функции а) \( \mathrm{y}=4 \mathrm{x}-2 \mathrm{x}^{3}+6 \mathrm{x}^{5} \quad \); б) \( f(x)=\frac{5}{x^{4}+4 x^{2}} \)

10. I en skål med 200 vindruvor är \( 90 \% \) gröna och resten blåa. Rickard äter enbart gröna vindruvor. Hur många vindruvor har Rickard ätit när andelen gröna vindruvor har minskat till \( 80 \% \) ?

2. \( \frac{1}{\sqrt{3}+\sqrt{2}} \div \frac{1}{\sqrt{4}+\sqrt{3}} \div \frac{1}{\sqrt{5}+\sqrt{4}}= \) ?