Find the range of the function
h(x)=5x2+20x+33x2+4x+7
Enter your answer in interval notation.
Ok, I found the answer.
We can use polynomial long division to simplify:
5x2+20x+33x2+4x+7=5−2x2+4x+7
Then, h(x)<5, and we can find the minimum by completing the square on the quadratic.
x2+4x+7=(x+2)2+3,
so the minimum is 3. Hence, the least possible value of h(x) is 133, and the range is h(x)∈[133,5)