Put the equation that is in general form:

Question

Y=x^2+18x+77 into standard form: Y=(x-h)^2+k

When I put my answers in for the first time I put y=(x+9)^2+4

how i did it was 18/2 which i got 9 and multiplied nine by itself and got 81 so i plugged it into the equation a different way with x^2+18x=y-77 which is x^2+18x+81=y-77+81 which then became y=(x+9)^2+4

and for the second time I put in y=(x+18)^2-4

and how i did it was i divided the b with 2 and the b was 18 so dividing 18 and 2 i got 9 and then i multiplied nine by itself and got 88 so it my equation became x^2+18x+81+77-81 then i wrote it in (x+18) (x+18)+77-81 which i then got y=(x+18)^2-4 but i got it wrong.

and I got both of them wrong to be honest I do not know where I went wrong

Answer 1

Hi Bailey,

Your first approach is actually very close. You know that x^2 + 18x = y - 77 and then x^2 + 18x +81 = y - 77+81. You could simplify it to (x+9)^2 = y + 4. Then what do you think you can do to have y = (x-h)^2 + k ?

Take some time to think about this. You got this! (think about what is -77+81)

Answer 2

stick with first way

but -81+77=-4 not +4

now y=(x+9)²-4=x²+18x+77