i need help with this one: find x by addition or substitution 4x+13y=40 4x+3y=-40
H hillariati New member Joined Sep 28, 2010 Messages 1 Sep 28, 2010 #1 i need help with this one: find x by addition or substitution 4x+13y=40 4x+3y=-40
M masters Full Member Joined Mar 30, 2007 Messages 378 Sep 28, 2010 #2 hillariati said: i need help with this one: find x by addition or substitution [1] 4x+13y=40 [2] 4x+3y=-40 Click to expand... Hi hillariati, To solve this system by addition, you will need to make either the x or y component of each equation additive inverses of each other. It is easy to make the x components additive inverses of each other. To do this, multiply equation [1] by -1 and add it to equation [2]. The x components add to zero, and you can easily solve for y. [1] -4x - 13y = -40 [2] 4x + 3y = -40 ---------------------- [3] -10y = -80 y = 8 You can now use substitution into [1] or [2] to find x.
hillariati said: i need help with this one: find x by addition or substitution [1] 4x+13y=40 [2] 4x+3y=-40 Click to expand... Hi hillariati, To solve this system by addition, you will need to make either the x or y component of each equation additive inverses of each other. It is easy to make the x components additive inverses of each other. To do this, multiply equation [1] by -1 and add it to equation [2]. The x components add to zero, and you can easily solve for y. [1] -4x - 13y = -40 [2] 4x + 3y = -40 ---------------------- [3] -10y = -80 y = 8 You can now use substitution into [1] or [2] to find x.
