Question 1178089: a-2b=9 2a-3b=4
Found 4 solutions by mananth, MathTherapy, josgarithmetic, ikleyn:
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! a-2b=9,
2a-3b=4
1.00 a + -2.00 b = 9.00
2.00 a + -3.00 b = 4.00 .............2
Eliminate b
multiply (1)by -3.00
Multiply (2) by 2.00
-3.00 a 6.00 b = -27.00
4.00 a -6.00 b = 8.00
Add the two equations
1.00 a = -19.00
/ 1.00
a = -19.00
plug value of a in (1)
1.00 a + -2.00 b = 9.00
-19.00 + -2.00 b = 9.00
-2.00 b = 28.00
b = -14.00
Ans a = -19.00
b = -14.00
Answer by MathTherapy(10551)  (Show Source):
You can put this solution on YOUR website!
a-2b=9 2a-3b=4
DON'T ever solve a problem like this the way the other person did! It's just UNHEARD of and ridiculously UNNECESSARY!
a - 2b = 9 ----- eq (i)
2a - 3b = 4 ---- eq (ii)
2a - 4b = 18 --- Multiplying eq (i) by 2 ------ eq (iii)
 ----- Subtracting eq (iii) from eq (ii)
Substitute - 14 for b in either eq (i) or (ii) to get the value of "a."
Answer by josgarithmetic(39616)  (Show Source):
Answer by ikleyn(52776)  (Show Source):
You can put this solution on YOUR website! .
The solution by @josgarithmetic giving the answer a= 37, b= -14 is INCORRECT.
I came to bring you the correct solution.
Your starting equations are
a - 2b = 9 (1)
2a - 3b = 4 (2)
To solve the system, express a = 2b + 9 from the first equation and substitute it into the second equation,
replacing "a" there. You will get
2*(2b+9) - 3b = 4
4b + 18 - 3b = 4
4b - 3b = 4 - 18
b = -14.
Now from equation (1), a = 2b + 9 = 2*(-14) + 9 = -28 + 9 = -19.
ANSWER. a= -19; b= -14.
CHECK. To check the solution, substitute the found values "a" and "b" into the original equations.
Solved (correctly).
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For your safety, ignore the post by @josgarithmetic.
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