algebra 2

posted by .

how do you solve
2x-y=7
-x+2y=-5 please show how you got this problem ! Thank you

  • algebra 2 -

    There are a couple of ways.

    First, the top equation says that y = 2x-7.
    So, substitute that into the bottom equation:

    -x + 2(2x-7) = -5
    -x + 4x - 14 = -5
    3x = 9
    x=3
    y=2x-7=6-7 = -1

    Another way is to remember that whole equations can be added and subtracted with each other, to give new equations. The goal of this method is to eliminate one or more variables by combining equations.

    This also relies on the fact that multiplyiong each term of an equation does not change the truth of the statement.

    So, multiply the bottom equation by 2 and then add the top equation:

    -2x + 4y = -10
    2x - y = 7

    Doing this yields

    0x + 3y = -3
    so, y = -1

    Now, plug that value into either of the original equations to see that x=3.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Algebra Problem

    I've gotten confunsed. Please help. Solve: 2y-a = a + 3b ____ ______, for y 3 4 Please show how to solve this. If you mean (2y -a)/3 = (a + 3b)/4 then 2y - a = (3/4) (a + 3 b) 2y = (7/4) a + (9/4) b y = (7/8) a + (9/8) b f(x)=x(squared)-4x+9 …
  2. Algebra

    I have some problems that I am having trouble with and I have some that need checking please. Thanks! Solve the equation. 4. (x+7/4)=2(x-1/6) Find all the value(s) of x that make thedenominator(s) zero. Then solve the equation. 6. …
  3. Algebra

    please help me with this question and check my answers. Solve the problem. A rectangle with width 2x + 5 inches has an area of 2x4 + 9x3 - 12x2 - 79x - 60 square inches. Write a polynomial that represents its length. ( I don't know …
  4. Algebra

    Once again, I have some confusing problems for math. If you know any answers, even if you only know one, please tell me the answer and walk me through it so I can actually understand how you get to it. Thanks! #1: A space craft travels …
  5. Algebra

    Use the formula C=2pi to find the radius, r, for a circle with a circumference of 160 centimeters. Round your answer to the nearest hundredth. a) 50.96 cm b) 28.08 cm c) 25.48 cm d) 80.00 cm When I tried to solve this problem, I never …
  6. algebra 1

    Can someone please help me with this inequality problem -3-8>(4x+8)-8 I have no idea how to solve this problem but I would like to learn. Can you be kind to show me the steps so that I can use this as an example problem for other …
  7. algebra

    I NEED HELP SOLVING THIS PROBLEM ,PLEASE EXPLAIN AND SHOW HOW TO SOLVE the answer ."I HAVE 63 LITERS OF HYDROGEN PEROXIDE, HOW MANY TEST TUBES CAN I FILL IF EACH CONTAINED 7/8 OF A LITER?
  8. Algebra 2

    Please help me solve and find the excluded values for this problem. Also please show me the work for this problem I want to learn!@!@!. 49X^6+7X^7/28X^8
  9. Algebra 2

    Please help me solve and find the excluded values for this problem. Also please show me the work for this problem I want to learn! h(x)=x^2-9/x^2-4x+3
  10. Algebra 2

    Please help me solve and find the excluded values for this problem. Also please show me the work for this problem I want to learn!F(h) = x^2-9/x^2-4x+3

More Similar Questions