Question 1080571
Use the elimination method to find the TWO solutions of this system. Mark TWO answers.

{y=9(x+4)^2 – 81
{y=−9(x+4)^2+81

	
(3, 0)
	
(-3, 0)
	
(5, 0)
	
(-1, 0)
	
(-7, 0)
	
(-9, 0)
<pre>{{{y = 9(x + 4)^2 - 81}}} ------- eq (i)
{{{y = - 9(x + 4)^2 + 81}}} ----- eq (ii)
2y = 0 ------- Adding eqs (ii) & (i)
y = 0

{{{0 = 9(x + 4)^2 - 81}}} ------- Substituting 0 for y in eq (i)
{{{81 = 9(x + 4)^2}}} ---------- Adding 81 to both sides
{{{9 = (x + 4)^2}}} ------------- Dividing each side by 9
{{{"" +- sqrt(9) = sqrt((x + 4)^2)}}} -------- Taking square root of both sides
{{{matrix(1,3, "" +- 3, "=", x + 4)}}}
{{{x = "" +- 3 - 4}}}
x = 3 - 4,    OR      x = - 3 - 4
x = - 1       OR      x = - 7
Solutions: {{{highlight_green(matrix(2,2, "(- 1,", "0)", "(- 7,", "0)"))}}}
That's how SIMPLE this is!!