Question

Answer 1

Câu 1:

1: \(\frac17\cdot\frac{-4}{9}+\frac17\cdot\frac{-14}{9}\)

\(=\frac17\left(-\frac49-\frac{14}{9}\right)\)

\(=\frac17\cdot\frac{-18}{9}=-\frac27\)

2: \(25\cdot\left(-\frac15\right)^3+\frac15-2\cdot\left(-\frac12\right)^2-\sqrt{\frac14}\)

\(=25\cdot\frac{-1}{125}+\frac15-2\cdot\frac14-\frac12\)

\(=-\frac15+\frac15-\frac12-\frac12=-1\)

Câu 2:

1:

a: \(\frac15+x=-\frac23\)

=>\(x=-\frac23-\frac15=\frac{-10-3}{15}=-\frac{13}{15}\)

b: |2-x|+0,73=4

=>|x-2|=4-0,73=3,27

=>x-2=3,27 hoặc x-2=-3,27

=>x=5,27 hoặc x=-1,27

2:

\(f\left(1\right)=3\cdot1^2-8=3-8=-5\)

\(f\left(-1\right)=3\cdot\left(-1\right)^2-8=3\cdot1-8=3-8=-5\)