Example 3: Solving systems by substitution | Systems of equations | 8th grade | Khan Academy

Solving systems by substitution 3

Missed the previous lesson?

8th grade on Khan Academy: 8th grade is all about tackling the meat of algebra and getting exposure to some of the foundational concepts in geometry. If you get this stuff (and you should because you're incredibly persistent), the rest of your life will be easy. Okay, maybe not your whole life, but at least your mathematical life. Seriously, if you really get the equations and functions stuff we cover here, most of high school will feel intuitive, even relaxing. (Content was selected for this grade level based on a typical curriculum in the United States.)

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[amandamartinez]

oh lord thank you. Becuase i have a test on this tommorow and i had no idea what i was doing and now i do!

[musing]

@Alfredhawkins01 : They are the same equation..or as Sal would probably say - equivalent lines.

[DarkChibiAngelX]

What about when you get equations like these?
8x=-2y-10
2x=4y
What do you do?

[DubstepDancer]

how would you solve
x+y=4
y=2x+1
my teacher doesnt help me at all so i have a d in algebra and these kinda problems confuse me. personally i dont think the alphabet should mix with numbers.

[rosenavratil]

Mr. Khan where are your arrows on the ends of your