Solve the system of equations algebraically. Show all of your steps.
y=x^2+2x
y=3x+20
Can someone please explain to me how to do this? I want to actually learn it, please.
Thanks! :)
Since you have two equations that equal y, you can set them equal to themselves, so 3x+20=x^2+2x
If you move those all over to one side, you get that x^2-x-20=0. From there you can factor out into two parts, (x-5)(x+4)=0. So for this set of equations you can know that the values of x where they intersect are -4 and 5.
All you need to do now is choose an equation to input the values in to solve for y. So, y= 3(-4)+20=8 when x=-4 and y=3(5)+20=35 when x=5. Therefore the two points at which they intersect are (-4,8) and (5,35)
is this right? ;-;
x^2+2x = 3x+20
x^2-x-20 = 0
(x-5)(x+4) = 20
x = 5, -4