№ 5 Алгебра = № 5 Математика
Розв’яжіть рівняння:
1) –5х = –20;
2) 7х – 11 = 2х + 1;
3) 9 – (5х + 1) = 10;
4) $2х = –1\frac{1}{5};$
5) 7 – 3х = –(2х – 7);
6) 9(х – 1) = 8х + 13.
Розв'язок:
1) –5х = –20,
–5х : (–5) = –20 : (–5),
х = 4;
2) 7х – 11 = 2х + 1,
7х – 2х = 1 + 11,
5х = 12,
$х = \frac{12}{5}=2\frac{2}{5};$
3) 9 – (5х + 1) = 10,
9 – 5х – 1 = 10,
8 – 5х = 10,
–5х = 10 – 8,
–5х = 2,
$х = –\frac{2}{5}=–0,4;$
4) $2х = –1\frac{1}{5},$
$2х = –\frac{6}{5},$
$х = –\frac{3}{5}=–0,6;$
5) 7 – 3х = –(2х – 7),
7 – 3х = –2х + 7,
–3х = –2х,
–3х + 2х = 0,
–х = 0,
х = 0;
6) 9(х – 1) = 8х + 13,
9х – 9 = 8х + 13,
9х – 8х = 13 + 9,
х = 22.