Question

РЕШИТЕ УРАВНЕНИЯ
АЛГЕБРА 7 КЛАСС
1. 7x + 10 = 5x + 12
2. 3(2x - 5) + 5x = 7
3. 5x - 3 = 6(2x + 5) + 2
4. 17x - 3(5x - 4) = 8(3x - 4)
5. 7(4x + 5) - 4(2 + 3x) =6x-3
6. 2,1(2 - x) + 1,4(1,5x – 3) =0​

Answer 1

1)

$7x + 10 = 5x + 12\\2x=2\\x=1$

2)

$3(2x - 5) + 5x = 7\\6x-15+5x=7\\11x=22\\x=2$

3)

$5x - 3 = 6(2x + 5) + 2\\5x-3=12x+30+2\\-35=7x\\x=-5$

4)

$17x - 3(5x - 4) = 8(3x - 4)\\17x-15x+12=24x-32\\44=22x\\x=2$

5)

$7(4x + 5) - 4(2 + 3x) =6x-3\\28x+35-8-12x=6x-3\\10x=-30\\x=-3$

6)

$2,1(2 - x) + 1,4(1,5x - 3) =0\\4,2-2,1x+2,1x-4,2=0\\42-21x+21x-42=0\\0x=0\\x\in \mathbb R$

Answer 2

1)7x+10=5x+12; 7x-5x=12-10; 2x=2; x=1
2)3(2x-5)+5x=7; 11x-15=7; 11x=7+15; 11x=22;
x=2;
3. 3)5-3=6(2x+5)+2; 5x-3= 12x +30+2; 5x-3=12x+32;5x-12x=32+3; -7x=35; x= -5;
4. 4)17x - 3(5x - 4) = 8(3x - 4); 17x-15x+12=24x-32; 2x+12=24x-32; 2x-24x=-32-12;-22x=-44; x=2;
5. 5)7(4x + 5) - 4(2 + 3x) =6x-3; 28x+35-8-12x=6x-3; 16x+27=6x-3; 16x-6x=-3-27; 10x=-30;x=-3;
6. 6)2,1(2 - x) + 1,4(1,5x – 3) =0; 4,2-2,1x+2,1x-4,2=0; 0+0=0; рівняння не має розв’язків.