Question

si f(x)=mx+b y f(2)=7
f(-2)=5, calcular el valor de m.b

Answer 1

armando un sistema de ecuaciones.

f(2) = 7
f(2) = mx+b
f(2) = m(2)+b = 7 ...(i)
_______________
f(-2)=5
f(-2) = mx +b
f(-2) = m(-2)+b = 5 ...(ii)

m(2)+b = 7 ...(i)
m(-2)+b = 5 ...(ii)

despejamos "b" en la ecuación ...(i)
m(2)+b = 7
b = 7-2m

reemplazamos b=7-2m en la ecuación ...(ii)

m(-2)+b = 5
-2m+(7-2m) = 5
-2m+7-2m = 5
-4m = -2
4m = 2
m = 2/4
m = ½

reemplazamos m=½ en la ecuación ...(i)
2m+b = 7
2(½)+b = 7
1+b = 7
b = 6

piden m.b
P = m.b
P = ½(6)
P = 3 <== Rpta.