A math teacher in my school wrote y=a(x+h)+k and the vertex is (-h,k). Isn’t that wrong?
A math teacher in my school wrote y=a(x+h)+k and the vertex is (-h,k). Isn’t that wrong? For example if you jave the polynomial x^2+6x+5
h would be -3 and k ould be -4. If u were to substitue the values of h and k into the teachers equation u would get (x-3)^2-4. When u expand that, the equation u get is x^2-6x+5, which os not the equation. the equation is supposed to be x^2+6x+5. Is the teacher right when she wrote y=a(x+h)^2+k and (-h,k)?
A math teacher in my school wrote y=a(x+h)+k and the vertex is (-h,k). Isn’t that wrong? For example if you jave the polynomial x^2+6x+5
h would be -3 and k ould be -4. If u were to substitue the values of h and k into the teachers equation u would get (x-3)^2-4. When u expand that, the equation u get is x^2-6x+5, which os not the equation. the equation is supposed to be x^2+6x+5. Is the teacher right when she wrote y=a(x+h)^2+k and (-h,k)?
1 Answer
There are two errors:
-
For consistency reasons, the vertex should always written as
#(h,k)# . The values of h and k can be any positive or negative real numbers but one should always write their variables as positive. -
The equation is incorrect. The correct equation is
#y = a(x-h)^2+k# ; it is important to always preserve the minus sign inside the square and the plus sign preceding k, because this prevents communication errors. For example, if the vertex is#(-2, -3)# , one should still write the equation as#y = a(x - (-2))^2+ (-3)# . Writing the equation as#y = a(x+2)^2 - 3# may cause someone to report that the vertex is#(2,3)#
