Expert: Richard J. Raridon - 5/11/2009

Question
QUESTION: I don't understand how to do any of the following problems Could you please help.

Directions: Find exact solution(s) of each system of equations using substitution or elimination.

1) y = x + 3
  y = 2x^2

2) y = 7 - x
  y^2 + x^2 = 9

3) y + x^2 = 3
  x^2 + 4y^2 = 36

ANSWER: 1) (3/2,9/2), (-1,2)
2) x = [7+/-(-31)]/2, y = [7-/+(-31)]/2
3) (0,3), (169/16, -11/4)

---------- FOLLOW-UP ----------

QUESTION: Could you show work so it is clear how to do the problem please.

Answer
1) x+3 = 2x^2, 2x^2-x-3= 0 = (2x-3)(x+1) so x = 3/2,-1
y = x+3 = 9/2 or 2
2) y^2 = 49-14x+x^2 so 49-14x+x^2+x^2 = 9
2x^2 -14x +40 = 0, x^2 -7x +20 = 0, x = [7 +/-(-31)^1/2]/2 and therefore, y = [7 -/+(-31)^1/2]/2
3) x^2 = 3-y so 3-y+4y^2 = 36
4y^2 -y -33 = 0 = (4y+11)(y-3) so y = 3,-11/4 and x = 0, 169/14