Question

a) 4x + 15=3x + 12
б) 0,04 (x-5) =0,5 (6+x)-2,5

Answer 1

( а )

$4x+15=3x+12\\\\4x-3x=12-15\\\\x=-3$

Проверка:

$4*(-3)+15=3*(-3)+12\\\\-12+15=-9+12\\\\-3=-3$

( б )

$0,04(x-5)=0,5(6+x)-2,5\\\\0,04x-0,2=3+0,5x-2,5\\\\0,04x-0,5x=3-2,5+0,2\\\\-0,46x=0,7\\\\x=-\frac{0,7}{0.46}$

Проверка:

$0,04 (-\frac{0,7}{0,46} -5) =0,5 (6-\frac{0,7}{0,46} )-2,5\\\\-\frac{0,028}{0,46}-0,2=3-\frac{0,35}{0,46}-2,5\\\\-\frac{0,028}{0,46}-\frac{0,092}{0,46}=\frac{1,38}{0,46}-\frac{0,35}{0,46}-\frac{1,15}{0,46}\\\\-\frac{0,12}{0,46}=\frac{1,03}{0,46}-\frac{1,15}{0,46}\\\\-\frac{0,12}{0,46}=-\frac{0,12}{0,46}$