-4x+8y=-256 -6y = x. how do u solve this equation by substitution.

1 answer:

4 0

To make it soo much easier, divide top equation by 4
-x+2y=-64

now
-6y=x
sub -6y for x
-(-6y)+2y=-64
6y+2y=-64
8y=-64
divide both sides by 8
y=-8

sub back
-6y=x
-6(-8)=x
48=x

x=48
y=-8
(x,y)
(48,-8)

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$x =( -2 + \sqrt{2^2 - 4*1*-16}) /2*1 \\x =( -2 + \sqrt{4 + 64}) /2\\x =( -2 + \sqrt{68} )/2\\x = ( -2 + \sqrt{4*17} )/2\\x = ( -2 + 2\sqrt{17} )/2\\x = - 1 + \sqrt{17}\\and\\\\x = - 1 - \sqrt{17}\\$