Question

Cho hàm số y= f(x)= 3- x

a) Tính f(-2); f(-1); f(0); f(1/2)

b) Tìm x biết y= 5; 2 ; -1

Answer 1

a) \(f\left(-2\right)=3-\left(-2\right)=5\)

\(f\left(-1\right)=3-\left(-1\right)=4\)

\(f\left(0\right)=3-0=3\)

\(f\left(\frac{1}{2}\right)=3-\frac{1}{2}=\frac{5}{2}\)

b) \(y=5\Rightarrow3-x=5\Rightarrow x=-2\)

\(y=2\Rightarrow3-x=2\Rightarrow x=1\)

\(y=-1\Rightarrow3-x=-1\Rightarrow x=4\)

Answer 2

a, \(y=f\left(-2\right)=3-\left(-2\right)=5\)

\(y=f\left(-1\right)=3-\left(-1\right)=4\)

\(y=f\left(0\right)=3-0=3\)

\(y=\left(\frac{1}{2}\right)=3-\frac{1}{2}=\frac{6-1}{2}=\frac{5}{2}\)

b,\(y=5\Rightarrow x=3-5=-2\)

\(y=2\Rightarrow x=3-2=1\)

\(y=-1\Rightarrow x=3-\left(-1\right)=3+1=4\)