My teacher said we are supossed to solve this using systems of equations:

Question

Let a, b, and c be real numbers such that a-7b+8c=4 and 8a+4b-c=7. Then a^2-b^2+c^2= ?

can someone please help?! i don't know what method to use to solve this or where to start

Answer 1

See answer here:
http://www.jiskha.com/display.cgi?id=1252885572