Answer:
[tex](d)\ x = 4[/tex]
Step-by-step explanation:
Given
[tex]f(x) = -x^2 + 4x + 12[/tex]
[tex]g(x) = x + 8[/tex]
Required
Find x such that: [tex]f(x) = g(x)[/tex]
This gives:
[tex]-x^2 + 4x + 12 = x+8[/tex]
Collect like terms
[tex]-x^2 + 4x -x + 12 -8=0[/tex]
[tex]-x^2 + 3x +4 =0[/tex]
Expand
[tex]-x^2 + 4x - x+4 =0[/tex]
Factorize
[tex]x(x - 4) - 1(x-4) = 0[/tex]
Factor out x - 1
[tex](x- 1)(x - 4)=0[/tex]
Solve:
[tex]x =1\ or\ x = 4[/tex]