solve the system by the linear combination method
a - 2b = 2
a + b = 2 (b+3)

Question

solve the system by the linear combination method 
  a - 2b = 2  
a + b = 2 (b+3)

anonymous · Answer

which 1 am r u trying to figure out

anonymous · Answer

both

whpalmer4 · Answer

Multiply the second equation by -1, and add it to the first.  This will give you an equation that only contains b.  Solve for b, then put the value for b in either of your original equations and solve for a.

anonymous · Answer

?

anonymous · Answer

sorry im confused

whpalmer4 · Answer

Equation 1: $$a-2b = 2$$Equation 2:$$a+b = 2(b+3)$$
Notice that the coefficient of a in both equations is just 1, so if we take the second equation and subtract it from the first, the a's will drop out and we'll be left with nothing but b and numbers.

$$a - 2b - a - b = 2 - 2(b+3)$$(I've written the first equation and subtracted out the corresponding sides of the second equation, in case what I did isn't clear)
$$-3b = 2 - 2b - 6 = -4b -4$$$$-3b + 4b = -4b -4 + 4b$$$$b=-4$$

Now use b = -4 in one of the original equations to solve for a.