177k views
4 votes
Find the maximum/minimum value of the quadratic function q² + 22q = y - 85 by

completing the square method.
O-36
O-48
C
-24
-64

User RezaNoei
by
8.4k points

1 Answer

5 votes

Explanation:

To find the maximum/minimum value of the quadratic function q² + 22q = y - 85, we can complete the square as follows:

q² + 22q = y - 85

q² + 22q + 121 = y - 85 + 121 (adding (22/2)² = 121 to both sides)

(q + 11)² = y + 36

Now, we have a square of a binomial on the left side, which means the minimum value of the quadratic function is y + 36, and it occurs when (q + 11) = 0. Thus, the minimum value is:

y + 36 = 36 - 85 = -49

Similarly, the maximum value of the quadratic function occurs when (q + 11) = 0, but this time the value of y will be as large as possible. The largest possible value of y occurs when STU is a permutation of the digits 9, 8, and 7 (since PQR must be 4, 0, and 3 in some order). Thus, the maximum value is:

y + 36 = 9 + 8 + 7 - 85 + 36 = -25

Therefore, the options are incorrect and the correct answers are:

Minimum value: -49

Maximum value: -25

User Icelava
by
9.4k points