## RedPrince 3 years ago 2x+y-3=0 x+2y+3=0 is these equations are solve like this:

1. waterineyes

Multiply first equation by 2 4x + 2y - 6 = 0 x + 2y + 3 = 0 Subtract them: 3x = 9 x = 3 Put the value of x in any of the above equation and find the value of y.. Can you do it or not??

2. RedPrince

@waterineyes I want to solve it simultaneously: look \[x/(1)(-3) + (2)(3) = -y/(-3)(2) + (1)(3) = 1/(2)(2) +(1)(1)\]

3. KRAZZy

yes waterineyes do it perfecly

4. waterineyes

@KRAZZy What???

5. RedPrince

@KRAZZy I know and I also solve it! But I forgot that how to solve equations simultaneously!

6. waterineyes

I studied this method but now forgot how to solve by this method but I will try wait for sometime...

7. RedPrince

8. KRAZZy

can any1 tell me wht is simultaneous methd:P

9. zepp

Are you referring to the reduction method?

10. zepp

If so (x+2y+3=0)*2 = 2x+4y+6=0

11. zepp

|dw:1340608303151:dw|

12. zepp

y=-3

13. zepp

?

14. waterineyes

Simultaneous Method says that: If two equations are like this: \[a_1x + b_1y + c_1 = 0\] \[a_2x + b_2y + c_2 = 0\] Then the method of Solving these equations by Cross Multiplication is: \[x/(b_1c_2 - b_2c_1) = y/((c_1a_2 - c_2a_1) = 1/(a_1b_2 - a_2b_1)\] Put in this the all the values and solve to get the values of x and y...

15. waterineyes

So, according to our question: \[a_1 = 2, b_1 = 1, c_1 = -3, a_2 = 1, b_2 = 2, c_2 = 3\] Put these values in formula given above: \[x/(3 + 6) = y/(-3 -6) = 1/(4-1)\] \[x/9 = y/(-9) = 1/3\] Equating one by one: x/9 = 1/3 x = 3 And y/(-9) = 1/3 y = -3 So, (x, y) is (3, -3).....

16. RedPrince

@waterineyes @zepp @KRAZZy O.k., I get it! now I understand what is wrong! I am just putting + singn agter multiplying but there is -ive sign!!! thanks to all!!!!!

17. waterineyes

Welcome dear..