Question

Cho các hàm số :

f1(x) = \(3x^2\); f2(x) = -5x; f3(x) = \(\frac{3}{x}\); f(4) = \(x^4\) + \(x^2\); f5(x) = \(x^4\) + \(x^2\).

a) Tính f1(\(\frac{1}{3}\)); f2(\(\frac{1}{5}\)); f3(3); f4(-1); f5(1)

b) Tính A = f1(0) + f2(5) + f3(3) + f4(-2) + f5(2)

c) So sánh f1(x) và f1(-x); f2(x) và -f2(-x)

d) Tìm x, biết: f5(x) =0: f5(x) =-1

Answer 1

a: \(f_1\left(\dfrac{1}{3}\right)=3\cdot\dfrac{1}{9}=\dfrac{1}{3}\)

\(f2\left(\dfrac{1}{5}\right)=-5\cdot\dfrac{1}{5}=-1\)

\(f3\left(3\right)=\dfrac{3}{3}=1\)

\(f4\left(-1\right)=1+1=2\)

f5(1)=1+1=2

b: \(A=3\cdot0^2+\left(-5\right)\cdot5+\dfrac{3}{3}+\left(-2\right)^4+\left(-2\right)^2+2^4+2^2\)

=-25+1+16+4+16+4

=-24+40

=16