Question

3x-7y=4
5x-3y=4
solve with addition method

Answer 1

15*x-35*y=20
15*x-9*y=12
-26*y=8
y=8/(-26) x=0.615

Answer 2

i still dont understand

Answer 3

Please, if I multiply both sides of the first equation by 5, I get:
\[5*(3x-7y)=5*4\]
or (1):
\[15x-35y=20\]
if I multiply both sides of the second equation by -3, I get:
\[-3*(5x-3y)=-3*4\]
or: (2)
\[-15x+9y=-12\]
now adding both sides of equation (1), with both sides of equation (2), we get:
\[(15x-35y)+(-15x+9y)=20+(-12)\]
or:(3)
\[-26y=8\]
dividing both sides of equation (3) by -26, we get:
\[y=\frac{ -26 }{ 8 }=-\frac{ 13 }{ 4 }\]

Answer 4

sorry the lastequation are non correct, I rewrite it:
\[y=-\frac{ 8 }{ 26 }=-\frac{ 4 }{ 13 }\]

Answer 5

next steo is to substitute y=-4/13, for example in the second eqation, namely :
5x-3y=4, so I can write:
\[5x-3*(-\frac{ 4 }{ 13 })=4\]
or:(4)
\[5x+\frac{ 12 }{ 13 }=4\]
mltipling both sides of equation (4) by 13, we get:
\[65x+12=52\]
then:
\[65x=40\]
dividig both sides of the above equation,by 65, we can write:
\[x=\frac{ 40 }{ 65 }=\frac{ 8 }{ 13 }\]

Answer 6

thanks

Answer 7

thanks!