<span> 2(4a+3b)-3(2a+6b)= 8a + 6b - 6a - 18b = 2a - 12b = -2(6b-a)= (-2)*(-1,9) = 3,8 </span>
{(x+1)(x^2-x+1)-x(x^2+4)<=9
{(x-3)(x+1)-(x-4)(x+4)>3
{x³+1-x³-4x-9≤0
{x²-3x+x-x²+16-3>0
{4x≥-8
{2x<10
{x≥-2
{x<5
x∈[-2;5)
сумма целых решений -2-1+0+1+2+3+4=7
ответ D) 7
5)
0.4х=-0.44
х=-0.44÷0.4
х=-1.1
6)
1/3х+1/9х=2/7-5/7
3/9х+1/9х=-3/7
4/9х=-3/7
х=-3/7÷4/9
х=-3/7×9/4=-27/28
7)
12а+15=17а-5
17а-12а=15+5
5а=20
а=4
4)
номер 4