Thread: substitute in x co ordinates to find y co ordiantes

i did all the working for this - the points of intersection for y=3x^2+5x-6 and y=-2x^2-3x+18 is when both eqations are same = 5x^2+8x-24 i found the two x valuesx1=1.532 and x2=-3.132 now i have to sub x co ordiantes to get the matching 2 y values.. ummm which formula do i sub it into and how? acan anyone help please

Originally Posted by studenthelp10

i did all the working for this - the points of intersection for y=3x^2+5x-6 and y=-2x^2-3x+18 is when both eqations are same = 5x^2+8x-24 i found the two x valuesx1=1.532 and x2=-3.132 now i have to sub x co ordiantes to get the matching 2 y values.. ummm which formula do i sub it into and how? acan anyone help please

or :

You have just found 2 x values for which the two equations for y are equal so can sub in either. You could of course check that your x values are correct by substituting in both and getting the same answers.

okay thanks ill try now

yup i got the right answer ! it matches the graphical points of the calculators thanks !