Type the ordered pair 2x + 5y = -9 3x - 4y = -2?
回答 (5)
2017-08-17 1:36 am
2x + 5y = -9 …… [1]
3x - 4y = -2 …… [2]
From [1] :
x = (-9 - 5y)/2 …… [3]
Substitute [3] into [2] :
3[(-9 - 5y)/2] - 4y = -2
6[(-9 - 5y)/2] - 8y = -4
3(-9 - 5y) - 8y = -4
-27 - 15y - 8y = -4
-23y = 23
y = -1
Substitute y = -1 into [3] :
x = [-9 - 5(-1)]/2
x = -2
3x - 4y = -2 …… [2]
From [1] :
x = (-9 - 5y)/2 …… [3]
Substitute [3] into [2] :
3[(-9 - 5y)/2] - 4y = -2
6[(-9 - 5y)/2] - 8y = -4
3(-9 - 5y) - 8y = -4
-27 - 15y - 8y = -4
-23y = 23
y = -1
Substitute y = -1 into [3] :
x = [-9 - 5(-1)]/2
x = -2
2017-08-17 1:31 am
2x + 5y = -9
3x - 4y = -2
8x + 20y = -36
15x - 20y = -10
23x = -46
x = -2
y = -1
(x, y) = (-2, -1)
I hope this helps.
3x - 4y = -2
8x + 20y = -36
15x - 20y = -10
23x = -46
x = -2
y = -1
(x, y) = (-2, -1)
I hope this helps.
2017-08-18 6:01 am
Nx = -9×-4 - 5×-2 = 46, Ny = 2×-2 - -9×3 = 23, D = 2×-4 - 5×3 = -23
(Nx/D, Ny/D) = (46/(-23), 23/(-23)) = (-2, -1)
(Nx/D, Ny/D) = (46/(-23), 23/(-23)) = (-2, -1)
參考: The intersection of ax+by=c and dx+ey=f is ((ce-bf)/(ae-bd), (af-cd)/(ae-bd)) where the lines are not parallel.
2017-08-17 2:16 am
8x + 20y = - 36
15x - 20y = - 10______add
23x = - 46
x = - 2
-4 + 5y = - 9
5y = - 5
y = - 1
x = - 2 , y = - 1
15x - 20y = - 10______add
23x = - 46
x = - 2
-4 + 5y = - 9
5y = - 5
y = - 1
x = - 2 , y = - 1
2017-08-17 1:44 am
OK multiply first equation by 3/2 we get 3x + 15/2y = -27/2 along with 3x -4y = -2, subtract second from first and we get 23/2*y = -23/2, so y = -1, plugging that into second equation we get 3x - 4(-1) = -2 -> 3x = -6 -> x = -2
So x = -2 and y = -1, so our equation is (-2, -1)
So x = -2 and y = -1, so our equation is (-2, -1)
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