Question

Diketahui fungsi f(x)= -2x² + 5 pada himpunan bilangan bulat
a. tentukan nilai fungsi f(-1)!
b. Jika f(x)= -45,tentukan nilai x!
c. Jika f(a)= -3,tentukan nilai a!

Answer 1

A.f(-1)=-2(-1)^2 + 5
= 2+5
=7
b.-45 =-2x^2 + 5
-45-5 =-2x^2
-50 =-2x^2
25 =x^2
5 =x
c.f(x)=f(a)
-3 = -2x^2 + 5
-3-5= -2x^2
-8 =-2x^2
4 = x^2
2 = x

Answer 2

A. f (-1) = -2(-1)^2 + 5
= 2^2 + 5
= 4 + 5 = 9

b. -45 = -2x^2 + 5
-45 - 5 = -2x^2
-50 = -2x^2
-50 / -2 = x^2
25 = x^2
x = 5

c. -2a^2 + 5 = -3
-2a^2 = -8
a^2 = -8 / -2
a^2 = 4
a = 2