Question

Помогите пожалуйста.

Answer 1

$12) frac{25 {x}^{2} - {y}^{2} }{10xy} div ( frac{1}{y} - frac{1}{5x} ) = frac{(5x - y)(5x + y)}{10xy} times frac{5xy}{5x - y} = frac{5x + y}{2} = frac{5 times 3 frac{2}{17} + 2 frac{7}{17} }{2} = frac{5 times frac{53}{17} + frac{41}{17} }{2} = frac{265 + 41}{34} = frac{306}{34} = 9$
$13)q = {i}^{2} rt \ q = 1960 \ i = 7 \ r = 8 \ 1960 = {7}^{2} times 8 times t \ 1960 = 392t \ t = frac{1960}{392} = 5c$

Answer 2

можете помочь??????? Срочно очень!!!!!

Answer 3

чем?