The pH scale for acidity is defined by \( \mathrm{pH}=-\log (H) \) where \( H \) is the concentration of hydrogen ions measured in moles per liter. A solution has a pH of 10.5 . Calculate the concentration of hydrogen ions in moles per liter. The exact concentration of hydrogen ions is Give the exact answer by using exponents.

Find the real solutions of the equation. (Enter your answers as a comma-separated list. If the solution is not (a) \( x^{3 / 5}=-8 \) \( x=\square x^{2 / 3}=16 \) (b) \( x=x^{4 / 3}=-64 \) (c) \( x=x^{2} \)

determine the evadrant in which the angles lies \( \begin{array}{ll}\text { a) } \frac{40 s^{\circ}}{} & \text { b) } \frac{\pi}{7}\end{array} \)

Prove that \( \triangle F G H \cong \triangle J K L \) are congruent \( \begin{array}{l}F(4,6) G(5,7) H(7,4) \\ J(1,-4) K(2,-5) L(4,-2)\end{array} \)

Mrs Brown gave \( \frac{4}{7} \) of her money to her son. He spent \( \frac{2}{5} \) of the money on a pair of shoes and the rest on two books that cost \( \$ 18 \) each. How much did Mrs Brown have at first?

8.3 จงหาฟังก์ชันเมื่อกำหนดค่าความยืดหยุ่นมาให้เป็น \( E=-\frac{0.2 P^{2}}{Q} \) และเมื่อราคาเป็น 15 บาทต่อหน่วย อุปสงค์เป็น 100 หน่วย