Câu 2.
a) `\frac{|x-1|}{5}=\frac{2}{7}`
`=>|x-1|=\frac{10}{7}`
`=>x-1=\frac{10}{7}`
`=>x=\frac{10}{7}+1=\frac{17}{7}`
`hoặc` `x-1=\frac{-10}{7}`
`=>x=\frac{-10}{7}+1=\frac{-3}{7}`
b) `\frac{5}{4}-\frac{1}{4}x=\frac{-1}{2}`
`=>\frac{1}{4}x=\frac{5}{4}+\frac{1}{2}`
`=>\frac{1}{4}x=\frac{7}{4}`
`=>x=\frac{7}{4}:\frac{1}{4}`
`=>x=7`
Câu 3.
a) `f(0)=2.0^{2}-10=0-10=-10`
`f(-1)=2.(-1)^{2}-10=2-10=-8`
`f(-1\frac{1}{2})`
`=f(-\frac{3}{2})`
`=2(-\frac{3}{2}\)^{2}-10`
`=\frac{9}{2}-10`
`=-9`
b) Vì `f(x)=2`
`=>2x^{2}-10=2`
`=>2x^{2}=12`
`=>x^{2}=12:2`
`=>x^{2}=6`
`=>x=±\sqrt{6}`
