China Naming Network - Ziwei Dou Shu - Weather in Yong 'an City, Sanming City
Weather in Yong 'an City, Sanming City
(1) Let the analytical formula of AB be y=kx+b,
Y = ∫ a (0,3) on kx+b, (1, 1.8),
∴b=3k+b= 1.8,
The solution is k =? 1.2b=3,
∴y=- 1.2x+3.
When x=5, y =- 1.2× 5+3 =-3.
The temperature at 5 o'clock is-3℃;
(2)∵ quadratic function y=-x2+mx+n passes through points B(5, -3) and C(8, 6)
∴? 25+5m+n=? 3? 64+8m+n=6
The solution is m = 16n =? 58
∴y=-x2+ 16x-58;
(3) When y=0,
From y=- 1.2x+3, x 1=2.5.
By y=-x2+ 16x-58
The solution is x2=8-6(8+6 is truncated);
X2-x 1 = 8-6-2.5 ≈ 3.05 > 3, anti-freezing measures are needed.