Question

Please Help! Will reward medal!

Answer 1

Solve the systems of equations algebraically. Show all of your steps.
y=x^2+2x
y=3x+20

Answer 2

@mathmale

Answer 3

@divyam_aisha

Answer 4

@Seratul do you know how to do this?

Answer 5

x^2+2x = 3x + 20
X^2 + 2x - 3x -20 = 0
x^2 - x - 20 = 0
and then simply solve for x using the quadratic formula

Answer 6

I don't know how to do that! :/

Answer 7

(don't forget that wolframalpha.com is a really useful)

Answer 8

so x=(-4,5)

Answer 9

\[x = \frac{ -b \pm \sqrt{b ^{2}+4ac}}{ 2a }\]

Answer 10

What numbers would I plug in?
Sorry I'm not very good at math!

Answer 11

ax^2 + bx + c = 0 where a,b and c are the constants in from of the x's
so a = 1, b = -1, and c = -20
and you should get two values x

Answer 12

https://www.khanacademy.org/math/algebra-basics/quadratics-polynomials-topic/solving-quadratics-factoring/v/example-1-solving-a-quadratic-equation-by-factoring

is a really good resource and this is a fundamental that you NEED to know

Answer 13

Okay! so
x= -4
x=5
y=8
y=35

Answer 14

is that correct?

Answer 15

Actually, you're supposed to solve this system of equations graphically. That means graphing both and then identifying the coordinates at which the 2 graphs intersect.
Can you graph the quadratic y=x^2+2x?

Can you graph the straight line y=3x+20?

Answer 16

yes

Answer 17

Please go ahead with this graphing. Even if your graph isn't perfect, you should be able to find one or two approx. sol'ns from your graph: look for the point or points of intersection of the 2 graphs and read off the coordinates of same.

Answer 18

the question states algebraically, but graphically is simpler

Answer 19

That is kind of what mine looked like!

Answer 20

Right idea. Need more detail, since you have to approx. the points of intersection.

Answer 21

www.wolframalpha.com/input/?i=y%3Dx%5E2%2B2x,+y%3D3x%2B20

Answer 22

This is exactly what mine looks like!

Answer 23

If you want to use wolframalpha, fine, but be aware you might have to be able to draw your own graphs and read off coordinates of pts of intersection from it.

Answer 24

okay!

Answer 25

so am i right when I got the answer to x and y or do I need to know more?

Answer 26

What are your approx. coordinates, please? I used wolframalpha and see that thre are 2 solutions. What are yours?

Answer 27

x=-4 x=5
y=8 y=35

Answer 28

My results were (-4,8) and (5,35). Same as yours. Great. Done.

Answer 29

okay! Thanks so much!

Answer 30

My great pleassure. Bye!