Question

Решите пж 3 уравнения даю 20 баллов а б в

Answer 1

( а )

$-20(x-13)=-220\\\\-20x+260=-220\\\\-20x=-220-260\\\\-20x=-480\\\\x=-480:(-20)\\\\x=24$

Проверка:

$-20(24-13)=-220\\\\-20*11=-220\\\\-220=-220$

( б )

$(30-7x)*8=352\\\\30*8-7x*8=352\\\\240-56x=352\\\\-56x=352-240\\\\-56x=112\\\\x=112:(-56)\\\\x=-2$

Проверка:

$(30-7*(-2))*8=352\\\\(30+14)*8=352\\\\44*8=352\\\\352=352$

( в )

$\frac{5}{12} y-\frac{3}{4} =\frac{1}{2}\\\\\frac{5}{12}y=\frac{1}{2}+\frac{3}{4}\\\\\frac{5}{12}y=\frac{2}{4}+\frac{3}{4} \\\\\frac{5}{12}y=\frac{5}{4}\\\\y=\frac{5}{4} :\frac{5}{12}\\\\y=\frac{5}{4}*\frac{12}{5} \\\\y=\frac{1}{1}*\frac{3}{1} \\\\y=\frac{3}{1} \\\\y=3$

Проверка:

$\frac{5}{12}*3-\frac{3}{4}=\frac{1}{2}\\\\\frac{5*3}{12}-\frac{3}{4}=\frac{1}{2} \\\\\frac{15}{12}-\frac{3*3}{4*3}=\frac{1}{2}\\\\\frac{15}{12}-\frac{9}{12}=\frac{1}{2}\\\\\frac{6}{12}=\frac{1}{2}\\\\\frac{1}{2}=\frac{1}{2}$