SOLUTION: xy=21 y=3x-2 could you please help me with this non-linear system of equations? I started the problem x(3x-2)=21 then I got 3x^2-2x-21=0, but I didn't know where to go from th

Algebra ->  Algebra  -> Systems-of-equations -> SOLUTION: xy=21 y=3x-2 could you please help me with this non-linear system of equations? I started the problem x(3x-2)=21 then I got 3x^2-2x-21=0, but I didn't know where to go from th      Log On

Ad: Algebra Solved!™: algebra software solves algebra homework problems with step-by-step help!
Ad: Algebrator™ solves your algebra problems and provides step-by-step explanations!

   

Question 32649: xy=21
y=3x-2
could you please help me with this non-linear system of equations?
I started the problem x(3x-2)=21 then I got 3x^2-2x-21=0, but I didn't know where to go from there. Question is from my homework, textbook: Stepping through college algebra one step at a time. author: Robert J Rapalje, Ed.D.
Thank you for your help.
Answer by Fermat(127) About Me  (Show Source):
You can put this solution on YOUR website!
You've gotten down to a quadratric equation. You can solve quadratic eqns by factorising or by using the quadratic formula if that doesn't work.
The quadratic formula is:x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ and is useed for solving a general quadratic expression which has been written in the form ax² + bx + c = 0.
Your quadratic expression is: 3x² - 2x - 21 = 0
This factorises as,
(3x + 7)(x - 3) = 0
So,
3x+7=0, or x-3=0
then,
x = -7/3, or x = 3
==================