Question

Determine the x-intercepts of the polynomial function y=-6(x+7)^4 + 5. Round to two decimal places, if necessary.

y=-6(x+7)^4 + 5
0=-6(x+7)^4 + 5
-5=6(x+7)^4
-5/6 =(x+7)^4

There are no x-intercepts??

Answer 1

Since it's a parabola opening downward, and is shifted up 5 units, you know that it will have two x-intercepts. So, what went wrong?

You lost a "-" sign after the 2nd line.

-5 = -6(x+7)^4
5/6 = (x+7)^4
±(5/6)^(1/4) = x+7
x = -7 ±(5/6)^(1/4) = -7 ± .955