maths

simultaneous equations

x + 2y = 4
3x - 4y = 7

x=3 and y = 1/2

i need to explain how i got this answer and do not know how to do that?

i am confused about how you got this answer what working out is it

the object in "elimination" is to get the coefficients of either the x or the y to be opposites, so that when you add the equations, they will cancel

so look at the first equation, if we multiply it by 2 we could have a 4y which is the opposite of -4y from the second equation.
let's do that

2x + 4y = 8 ....... the first times 2
3x - 4y = 7 ........ no change
------------
5x + 0 = 15 .........I added them
x=3 ..................I divided both sides by 5

now take that x value and substitute it back into the easier of the two original equation to get y = 1/2

  1. 👍 0
  2. 👎 0
  3. 👁 114
asked by Vicki

Respond to this Question

First Name

Your Response

Similar Questions

  1. math

    solve the simultaneous equations to find the coordinates of the point of intersection for the pair of lines of the simultaneous equations. Then check the answer by graphing the equations 3x-y=-4 2x-y=0

    asked by Lauren on October 16, 2010
  2. Math

    A particular Chemistry book costs $6 less than a particular Physics book. Two such Chemistry books and three such Physics books cost a total of $123. Construct two simultaneous equations and solve them using the substitution

    asked by anonymous on February 23, 2018
  3. Engineering

    I need help solving the following simultaneous equations, for the values of Vo and a: 1.4 = Vo e^-32a 4 = Vo e^-6a I've never come across simultaneous equations like this (e is the base of natural logarithms, so perhaps taking

    asked by Stuart on May 13, 2007
  4. math

    how do i solve two step equations? Do you mean two equations in two unknowns? The method of substitution is one way. There is a good tutorial here: http://www.themathpage.com/alg/simultaneous-equations.htm

    asked by megan on January 18, 2007
  5. maths pls help

    1. Solve the following simultaneous equations: log2 xy = 7 log2 (x^2/y) = 5 2. If log y x =a and log z x=b where x is not equal to 1, express the following in terms of a and b: logy (yz) Solve the following simultaneous equations:

    asked by Claire on November 21, 2007
  6. Maths

    Its the old rabbit colony question using simultaneous linear and quadratic equations - and I need help: A colony of rabbits is growing so that the total number of rabbits (R) after number of weeks (t) is shown: on this table. t=5

    asked by LivviC on March 6, 2010
  7. math

    Explain why the simultaneous equations y=1/2x+2 and 2y-x:4 have an infinite number of solutions. What is diffrent about these equations compared with the equations in the first question ( the equations were y=2x+3 and 5y-10x=5)?

    asked by CJ on February 24, 2011
  8. Maths

    Simultaneous equations... y = x^2 - x - 1 y = 2 - 3x Many thanks.

    asked by Anonymous123 on September 21, 2016
  9. mathamatics

    what is the value of X and Y for following simultaneous equations, X + Y = 3 2X - Y = 9

    asked by JAndu on June 6, 2010
  10. math

    Part of the road is to be on a parabolic curve given by a function of the form y = ax2 + bx + c where x and y are local co-ordinates. The road alignment must pass through the following 3 points:- x = 150m y = 190.650m x = 300m y =

    asked by k on December 16, 2016
  11. Physics

    Two events that are simultaneous in one frame of reference will be: A) simultaneous in all frames of reference B) simultaneous in another frame that is moving in the opposite direction C) simultaneous in another frame of reference

    asked by Jeff on January 12, 2010

More Similar Questions