K kizzy101 New member Joined Aug 29, 2005 Messages 1 Aug 29, 2005 #1 i forgot how to do problems like this , and it has to be solved by substitution: 8x - 2y = 58 6x - 2y = 40 if someone would help i will be forever greatful !
i forgot how to do problems like this , and it has to be solved by substitution: 8x - 2y = 58 6x - 2y = 40 if someone would help i will be forever greatful !
G Guest Guest Aug 29, 2005 #2 8x - 2y = 58 6x - 2y = 40 Two methods exist to solve these problems subtract the 2 equations and the y variable will cancel out. 8x-2y-(6x-2y) =58-40 8x-2y-6x+2y =18 2x=18 x=9 sub this back into either of the original equations and you will be done.
8x - 2y = 58 6x - 2y = 40 Two methods exist to solve these problems subtract the 2 equations and the y variable will cancel out. 8x-2y-(6x-2y) =58-40 8x-2y-6x+2y =18 2x=18 x=9 sub this back into either of the original equations and you will be done.
S soroban Elite Member Joined Jan 28, 2005 Messages 5,584 Aug 30, 2005 #3 Hello, kizzy101! Solve by substitution: [1] . 8x - 2y = 58 [2] . 6x - 2y = 40 Click to expand... (1) Solve one of the equations for one of its variables. . . . Solve [1] for y: .-2y .= .-8x + 58 . ---> . y .= .4x - 29 . (a) (2) Substitute into the other equation. . . . 6x - 2(4x - 29) .= .40 . . . . . 6x - 8x + 58 .= .40 . . . . . . . . . . . . -2x .= .-18 . . . . . . . . . . . . . .x .= .9 Substitute into (a): . y .= .4(9) - 29 .= .7 Answer: . (x, y) .= .(9, 7)
Hello, kizzy101! Solve by substitution: [1] . 8x - 2y = 58 [2] . 6x - 2y = 40 Click to expand... (1) Solve one of the equations for one of its variables. . . . Solve [1] for y: .-2y .= .-8x + 58 . ---> . y .= .4x - 29 . (a) (2) Substitute into the other equation. . . . 6x - 2(4x - 29) .= .40 . . . . . 6x - 8x + 58 .= .40 . . . . . . . . . . . . -2x .= .-18 . . . . . . . . . . . . . .x .= .9 Substitute into (a): . y .= .4(9) - 29 .= .7 Answer: . (x, y) .= .(9, 7)
, and it has to be solved by substitution: