Question

dada a funçao f(x)=x2+2x-5 determine
a)f(1)
b)f(2)
c)f(0)
d)f(√2)
e)f(-2)
f)f(½)

Answer 1

a) f(1) = - 1 

f(x) = x2 + 2x - 5 
f(1) = 1.2 + 2.1 - 5
f(1) = 2 + 2 - 5
f(1) = - 1

b) f(2) = 3

f(x) = x2 + 2x - 5 
f(2) = 2.2 + 2.2 - 5
f(2) = 4 + 4 - 5
f(2) = 8 - 5
f(2) = 3

c) f(0) = - 5

f(x) = x2 + 2x - 5 
f(0) = 2.0 + 2.0 - 5
f(0) = 0 + 0 - 5
f(0) = - 5 

d) f(√2) = 4√2 - 5

f(x) = x2 + 2x - 5 
f(√2) = √2.2 + 2.√2 - 5
f(√2) = 4√2 - 5

e) f(- 2) = -13

f(x) = x2 + 2x - 5 
f(- 2) = - 2.2 + 2.(-2) - 5
f(- 2) = - 4 - 4 - 5 
f(- 2) = - 13

f) f(½) = - 3

f(x) = x2 + 2x - 5 
f(½) = (½).2 + 2.(½) - 5
f(½) = (2/2) + (2/2) - 5
f(½) = 1 + 1 - 5
f(½) = - 3