Пошаговое объяснение:
1) { 4 x + 5 y = 1
{6 x + 8 y = 14 ⇒
{y = − 0 , 8 x + 0 , 2
{6 x + 8 y = 14 ⇒
{ y = − 0 , 8 x + 0 , 2
{6x + 8 ( − 0 , 8 x + 0 , 2 ) = 14 y ⇒
{y = − 0 , 8 x + 0 , 2
{− 0 , 4x − 12, 4 = 0 ⇒
{y = − 0 , 8 x + 0 , 2
{x = − 31 ⇒
{y = 25
{x = − 31.
2) {6 x + 7 y = 2
{3 x − 4 y = 46 ⇒
{y = − 6 /7 x + 2 /7
{3 x − 4 y= 46 ⇒
{ y = − 6/ 7 x + 2/ 7
{3 x − 4 ( − 6/ 7 x + 2 /7 ) = 46 ⇒
{y = − 6 /7 x + 2/ 7
{45/ 7 x − 330 /7 = 0 ⇒
{y = − 6 /7 x + 2/ 7
{x = 22/ 3 ⇒
{y = − 6
{x = 22/ 3 .
Надеюсь всё понятно.
(25 - 8 3/4) + (13 5/12 - 2 11/18) - (2 2/9 - 1 3/4) = 9 7/12
1) 25 - 8 3/4 = 24 4/4 - 8 3/4 = 16 1/4
2) 13 5/12 - 2 11/18 = 13 15/36 - 2 22/36 = 12 51/36 - 2 22/36 = 10 29/36
3) 2 2/9 - 1 3/4 = 2 8/36 - 1 27/36 = 1 44/36 - 1 27/36 = 17/36
4) 16 1/4 + 10 29/36 = 16 9/36 + 10 29/36 = 26 38/36 = 27 2/36
5) 27 2/36 - 17/36 = 26 38/36 - 17/36 = 9 21/36 = 9 7/12
12 7/10 - 3 1/2 - (4 1/2 - 3 3/4) = 8 9/20
1) 4 1/2 - 3 3/4 = 4 2/4 - 3 3/4 = 3 6/4 - 3 3/4 = 3/4
2) 12 7/10 - 3 1/2 = 12 7/10 - 3 5/10 = 9 2/10
3) 9 2/10 - 3/4 = 9 4/20 - 15/20 = 8 24/20 - 15/20 = 8 9/20
