18. A circle in the standard (x,y) coordinate plane is
1 answer:
9514 1404 393
Answer:
F
Step-by-step explanation:
If the circle is tangent to the x-axis at 4, the center lies on the line x=4.
If the circle is tangent to the y-axis at 4, the center lies on the line y=4.
If the center of the circle is (x, y) = (4, 4) and it is tangent to the axes, then the radius is 4.
The standard-form equation of the circle centered at (h, k) with radius r is ...
(x -h)² +(y -k)² = r²
For the values (h, k) = (4, 4) and r = 4, the equation is ...
(x -4)² +(y -4)² = 16 . . . . . . matches choice F
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Answer:
(c) an = 4·(1/3)^(n-1)
Step-by-step explanation:
The explicit rule for a geometric sequence with first term a1 and common ratio r is ...
an = a1·r^(n-1)
The factor in the recursive rule tells you the common ratio is 1/3, so the explicit rule is ...
an = 4·(1/3)^(n-1) . . . . . . matches choice C
