Răspuns:
-b/2a==-(5-3a)/2a=4
(3a-5)=8a
3a-8a=5
-5a=5
a= -1
f(x)=-x²+8x+c
-Δ/4a=-(64+4c)/(-4)=16
16+c=16 c=0
f(x)= -x²+8x=x(8-x)
f(1)=1*7=7
f(2)=12
f(3)=15
ff(4)=16
f(5)=15
f(6)=12
f(7)=7
f(8)=0
f(9)=-9
f(10)=-20
∑₁¹⁰f(xi)=50
∑f(xi)=f(1)+f(2)+f(3)+...+f(10)=7+12+15+...+7-9-20=50
Explicație pas cu pas:
