Вправа 279 алгебра Бевз гдз 7 клас

№ 279

а) (4х – 5) – (7х + 8) = 2
4х – 5 – 7х – 8 = 2
–3х = 2 + 13
х = 15 : (–3)
х = –5;

б) 9z + 17 – (4z – 6) = 38
9z + 17 – 4z + 6 = 38
5z = 38 – 23
z = 15 : 5
z = 3;

в) (5х + х³ – 7) – (2ха + 3х) = –(1 + х³)
5х + х³ – 7 – 2х³ – 3х = –1 – х³
2х = –1 + 7
х = 6 : 2
х = 3;

г) 19 – (3х² – 2х) – (6х – х²) = 7 – 2х²
19 – 3х² + 2х – 6х + х² = 7 – 2х²
–4х = 7 – 19
х = –12 : (–4)
х = 3.

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