X2 – 1x – 90 = 0 has solutions {a, b}. What is a + b?
1 answer:
You might be interested in
9514 1404 393
Answer:
10. (x, y) = (-3/8, 2 9/16)
11. k = -1
Step-by-step explanation:
10. The value of x at the vertex is ...
x = -b/(2a)
x = -(-3)/(2(-4)) = -3/8
The corresponding value of y is ...
y = 2 +(-3/8)(-3 +(-3/8)(-4)) = 2 +(-3/8)(-3/2) = 2 +(9/16)
The vertex is (x, y) = (-3/8, 2 9/16).
__
11. The discriminant is zero when the roots are equal.
b² -4ac = 0
(k-1)² -4(1)(-k) = 0
k² -2k +1 +4k = 0
k² +2k +1 = 0 . . . . . collect terms
(k +1)² = 0 . . . . . . . . write as a square
k = -1 . . . . . . . . . . . . the value of k that satisfies
<em>Check</em>
x² -2x +1 = (x -1)² = 0 . . . . has equal roots: x=1.
