Алгебра 7 клас
Знайдіть розв’язок системи рівнянь:
1) 4х+у=12
7х+2у=20
2) х-2у=5
3х+8у=1
3) 4у-х=11
5х-2у=17
4) 6х-у=-1
2х-3у=-11
5) х+у=7
9у-2х=-25
6) 5х-3у=0
15х+2у=55.
More Questions From This User See All
Copyright © 2024 SCHOLAR.TIPS - All rights reserved.
Answers & Comments
Ответ:
1)7x + 2(12 - 4x) = 20
7x + 24 - 8x = 20
-x = -4
x = 4
4(4) + y = 12
4(4) + y = 12y = 12 - 16
4(4) + y = 12y = 12 - 16y = -4
(x, y) = (4, -4)
2)3(5 + 2y) + 8y = 1
3(5 + 2y) + 8y = 115 + 6y + 8y = 1
3(5 + 2y) + 8y = 115 + 6y + 8y = 114y = -14
3(5 + 2y) + 8y = 115 + 6y + 8y = 114y = -14y = -1
x - 2(-1) = 5
x - 2(-1) = 5x + 2 = 5
x - 2(-1) = 5x + 2 = 5x = 3
(x, y) = (3, -1)
3)5(4y - 11) - 2y = 17
5(4y - 11) - 2y = 1720y - 55 - 2y = 17
5(4y - 11) - 2y = 1720y - 55 - 2y = 1718y = 72
5(4y - 11) - 2y = 1720y - 55 - 2y = 1718y = 72y = 4
4(4) - x = 11
4(4) - x = 1116 - x = 11
4(4) - x = 1116 - x = 11x = 5
(x, y) = (5, 4)
4)2x - 3(6x + 1) = -11
2x - 3(6x + 1) = -112x - 18x - 3 = -11
2x - 3(6x + 1) = -112x - 18x - 3 = -11-16x = 8
2x - 3(6x + 1) = -112x - 18x - 3 = -11-16x = 8x = -0.5
6(-0.5) - y = -1
6(-0.5) - y = -1-3 - y = -1
6(-0.5) - y = -1-3 - y = -1y = 2
(x, y) = (-0.5, 2)
5)9y - 2(7 - y) = -25
9y - 2(7 - y) = -259y - 14 + 2y = -25
9y - 2(7 - y) = -259y - 14 + 2y = -2511y = -11
9y - 2(7 - y) = -259y - 14 + 2y = -2511y = -11y = -1
x + (-1) = 7
x + (-1) = 7x = 8
(x, y) = (8, -1)
6)15x + 2(5/3)x = 55
15x + 2(5/3)x = 5515x + (10/3)x = 55
15x + 2(5/3)x = 5515x + (10/3)x = 5545x + 10x = 165
15x + 2(5/3)x = 5515x + (10/3)x = 5545x + 10x = 16555x = 165
15x + 2(5/3)x = 5515x + (10/3)x = 5545x + 10x = 16555x = 165x = 3
5(3) - 3y = 0
5(3) - 3y = 015 = 3y
5(3) - 3y = 015 = 3yy = 5
(x, y) = (3, 5)
Объяснение:
:)