Grade 10-Math

posted by .

x+2y=3
5x+4y=8

I isolated x+2y=3 to make: x=3-2y
then i began to sub in equation one with equation two:
5x+4y(3-2y)=8
5x+12-8y=8

after that i began to try to solve the equation but my answers were not correct. any help would be greatly appreciated!

  • Grade 10-Math -

    You are substituting for y instead of x
    Besides that you were still keeping the y as well.

    5(3-2y) + 4y = 8
    15 - 10y + 4y = 8
    -6y = -7
    y = 7/6

    then in x = 3-2y
    x = 3-14/6 = 2/3

    x = 2/3 , y = 7/6

  • Grade 10-Math -

    i understand how you got the answer i just don't get why i don't put 5x+4y before the equation because i have been for all the other ones and i got those ones right..

    for example this one:
    6x+5y= 7
    x-y= 3
    i isolated the second equation into y=3+x

    so: 6x+5y(3+x)=7
    6x+15+5x=7
    6x+5x-15+15=7+15
    11/11= 22/11
    x=2

    then i subbed in the other equation..
    6(2)+5y=7
    12+5=7-12
    5y/5= -5/5
    y= -1

    and i checked my answer and it was correct.
    i just don't understand what i'm doing wrong for the equation.. because i keep thinking the full equation must go first not separate it.

  • Grade 10-Math -

    Horizontal line through(5,0)

  • Grade 10-Math -

    -2(2y+15)<-6y-14

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. DRWLS CAN YOU ANSWER

    How do i solve inequalitites with three variables. I still can't figure it outplease help. x+y=1 y-z=-3 2x+3y+z=1 THE ANSWERS ARE3,-2,1 HOW DID THEY GET THAT ANSWER. This can be solved a number of ways. 1) subsitition 2) determinants …
  2. math

    can anyone help with this? suppose you bought some 32 cents stamps and some 20 cents stamps. you spent $3.92 for 16 stamps. how many of each stamp did you buy?
  3. math

    x+y= 30 4x+2y=74 y+ What does the y+ signify?
  4. Algebra2

    Find the polynomials roots to each of the following problems: #1) x^2+3x+1 #2) x^2+4x+3=0 #3) -2x^2+4x-5 #3 is not an equation. Dod you omit "= 0" at the end?
  5. alg.

    solve the system by addition: -5x-9y = -5 x+5y=-15 I've tried this one over and over, but I can't seem to get the right answer. I don't even really know where to start. each time i try to do it, i go about it a little differently and …
  6. Algebra

    I have a few questions that I need help with. Solve the radical equation, and check all proposed solutions. 5. x- square root 3x-2=4 I don't understand this problem. Solve and check the equation. 10. (x^2+14x+49)^3/4-20=7 would I have …
  7. 8th grade math

    how do you make an equation that is parallel to another equation?
  8. math

    A hot air balloon was at a height of 60 feet above the ground when it began to ascend. The balloon climbed at a rate of 15 feet per minute. a) make a table that shows the height of the air balloon after climbing for 1,2,3,&4 minutes. …
  9. math- can you please check my work

    Can you please check my work. I asked this question yesterday but no one helped me. Thank you , I really appreciate it A hot air balloon was at a height of 60 feet above the ground when it began to ascend. The balloon climbed at a …
  10. math

    compare and contrast: below are two equations. solve each equation and compare the two solutions. choose the statement that is true about each solution. equation #1 2x-3=-17 5x+3=12 A. equation #1 and equation #2 have the same number …

More Similar Questions