Question

If f(x) = x3+ x2and g(x) = x4+ x2+ x, what is the value of f(x) –g(x) when x = 1?
A) -2
B) -1
C) 1
D) 5

Answer 1

Answer:

B) -1

Step-by-step explanation:

$f(x)=x^3+x^2\\\\g(x)=x^4+x^2+x$

METHOD 1

$f(x)-g(x)=(x^3+x^2)-(x^4+x^2+x)=x^3+x^2-x^4-x^2-x\\\\=-x^4+x^3-x\\\\x=1\\\\-1^4+1^3-1=-1+1-1=-1$

METHOD 2

$x=1\\\\f(1)=1^3+1^2=1+1=2\\\\g(1)=1^4+1^2+1=1+1+1=3\\\\f(1)-g(1)=2-3=-1$