Question

Tìm nghiệm:

a) f(x)=-5x-4

b)f(x)=13-3x

c)h(x)=-15+5x

d)k(x)=4/5 x + 16/25

Answer 1

a) Đặt f(x)=0

\(\Leftrightarrow-5x-4=0\)

\(\Leftrightarrow-5x=4\)

hay \(x=-\frac{4}{5}\)

Vậy: \(S=\left\{-\frac{4}{5}\right\}\)

b) Đặt F(x)=0

\(\Leftrightarrow13-3x=0\)

\(\Leftrightarrow3x=13\)

hay \(x=\frac{13}{3}\)

Vậy: \(S=\left\{\frac{13}{3}\right\}\)

c) Đặt h(x)=0

\(\Leftrightarrow-15+5x=0\)

\(\Leftrightarrow5x=15\)

hay x=3

Vậy: S={3}

d) Đặt k(x)=0

\(\Leftrightarrow\frac{4}{5}x+\frac{16}{25}=0\)

\(\Leftrightarrow\frac{4}{5}x=-\frac{16}{25}\)

hay \(x=-\frac{16}{25}:\frac{4}{5}=\frac{-16}{25}\cdot\frac{5}{4}=-\frac{80}{100}=-\frac{4}{5}\)

Vậy: \(S=\left\{-\frac{4}{5}\right\}\)