simultaneous equations

x + 2y = 4

3x - 4y = 7

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- Apr 15th 2007, 07:14 AMvtaylorsimultaneous equations urgant for homework
simultaneous equations

x + 2y = 4

3x - 4y = 7 - Apr 15th 2007, 07:21 AMearboth
Hello,

there are a lot of different ways to solve such a system of equations. Here is one:

A: x + 2y = 4 ===> x = 4 - 2y

B: 3x - 4y = 7 Now plug in the term for x from equation A:

3(4 - 2y) - 4y = 7

12 - 6y -4y = 7

-10y = - 5

**y = ½**Plug in this value into equation A:

**x**= 4 - 2*½ =**3** - Apr 15th 2007, 07:43 AMSoroban
Hello, vtaylor!

Another method . . . "Elimination"

Quote:

. . .x + 2y .= .4 .[1]

. . 3x - 4y .= .7 .[2]

Multiply [1] by 2: . 2x + 4y .= .8

. . . . . . Add [2]: . 3x .- 4y .= .7

And we have: . 5x = 15 . → .**x = 3**

Substitute into [1]: .3 + 2y .= .4 . → .**y = ½**

- Apr 15th 2007, 07:51 AMearboth
- Apr 15th 2007, 10:19 AMrj2001
good review this is on my final next week