Question

são dados f(x)=ax²+bx+c , f(1)=-1 , f(0)=-2 e f(3)=-5.Determine a,b,c.

Answer 1

a.(1)²+b(1)+c= - 1 ==> a + b -2=-1 ==> a+b = -1+2 ==>a+b= 1
a(0)²+b(0)+c= - 2 ==> c = - 2
a(3)²+b(3)+c= - 5 ==> 9a+ 3b -2= -5==> 9a+3b=-5+2==> 9a+3b= - 3(:3)==> 3a+b= - 1

   a+b= 1(-1)
 3a+b= - 1

    - a -b = - 1
    3a +b = -1
         2a = - 2
           a = - 1

a+b= 1 ==> - 1 + b = 1 ==>b = 1+1 ==>b =2