Asked by Black Rose
solve the systems of equations algebraically. please show all your steps.
y=x^2+2x
y=3x+20
y=x^2+2x
y=3x+20
Answers
Answered by
Reiny
since both are expressed as y = ...
we can equate them:
x^2 + 2x = 3x + 20
x^2 - x - 20 = 0
(x-5)(x+4) = 0
x = 5 or x = -4
if x = 5, y = 3(5) + 20 = 35
if x = -4, y = 3(-4) + 20 = 8
x=5, y = 35
x = -4, y = 8
check:
http://www.wolframalpha.com/input/?i=solve+y%3Dx%5E2%2B2x,++y%3D3x%2B20
we can equate them:
x^2 + 2x = 3x + 20
x^2 - x - 20 = 0
(x-5)(x+4) = 0
x = 5 or x = -4
if x = 5, y = 3(5) + 20 = 35
if x = -4, y = 3(-4) + 20 = 8
x=5, y = 35
x = -4, y = 8
check:
http://www.wolframalpha.com/input/?i=solve+y%3Dx%5E2%2B2x,++y%3D3x%2B20