You are here:

Basic Math/X=4Y+5 X=3Y-2 what do...

Advertisement

Expert: - 1/5/2005


Question
X=4Y+5
X=3Y-2

what do i do i no i have to solve for x or somethin im not sure

3X-5Y=11
X-3Y=1


Y=1/2X+3
Y=2X-1  

Answer
Hello Shannon,

One way to solve these is to take one of the
equations and solve for one of the variables...
then substitute into the other equation.  I'll
illustrate this for:
3X-5Y=11
X-3Y=1
Solving the 2nd equation for x gives: x=1+3y
now substitute that into the 1st equation (for x):
3(1+3y)-5y=11 ==> 3+9y-5y=11 ==> 3+4y=11
==> 4y=8 ==> y=2, so x=1+3(2)=7...so x=7, y=2

OK, get the idea?

Abe

Basic Math

All Answers

Answers by Expert:

Ask Experts

Volunteer

Abe Mantell

Expertise

Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!

Experience

Over 15 years teaching at the college level.

Organizations belong to
NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.

Education/Credentials
B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook

©2012 About.com, a part of The New York Times Company. All rights reserved.