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About 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
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

You are here: Experts > Science > Math for Kids > Algebra > Linear Combinations

Algebra - Linear Combinations

Expert: Abe Mantell - 1/8/2008

Question
I need help with this particular problem on my math homework!

5e + 4f = 9
4e + 5f = 9

Thank you!!

Answer
Hello Melissa,

I gather the problem is to solve for 'e' and 'f'...

One way is by "elimination"...
multiply the 1st equation by 4, and the 2nd equation by -5
to get:
20e+16f=36 and
-20e-25f=-45...now add them!
=============
-9f=-9 ==> f=1, then substitute this into either equation
to solve for 'e'...e=1 as well.

OK? TTYL, Abe

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