2007-12-09 18:44:19 · 4 answers · asked by gr8ventura 1 in Science & Mathematics ➔ Mathematics
since y equals x^2-3x-9 and 2x+5, then
x^2-3x-9 =2x+5
just solve to get all the terms in one side
x^2-5x-14=0
and factorize
(x+2)(x-7)=0 therefore x=7 or x=-2
since y=2x+5
if x=7 >>> y=19
if x=-2 >>> y=1
2007-12-09 18:49:47 · answer #1 · answered by Sergio__ 7 · 1⤊ 0⤋
y = x^2 - 3x - 9 ---------- (1)
y = 2x + 5 ---------- (2)
(1) = (2)
x^2 - 3x - 9 = 2x + 5
x^2 - 5x - 14 = 0
(x - 7)(x + 2) = 0
x = 7 or - 2
When x = 7, y = 2(7) + 5 = 19
When x = -2, y = 2(-2) + 5 = 1
2007-12-10 02:50:51 · answer #2 · answered by Blake 3 · 1⤊ 1⤋
2x + 5 = x² - 3x - 9
x² - 5x - 14 = 0
(x - 7)(x + 2) = 0
x = 7 , x = - 2
2007-12-10 03:55:12 · answer #3 · answered by Como 7 · 2⤊ 0⤋
equate them, then use quadratic equation
2x+5=x²-3x-9
0 = x² - 5x - 14
(x -7)(x + 2)
2007-12-10 02:47:59 · answer #4 · answered by Quality Post 2 · 0⤊ 0⤋