cho hàm số y=f(x)=|2x-1|+2 a,Tính f(-3);f(2/5) b,Tìm x sao cho f(x)=6 12/08/2021 Bởi Katherine cho hàm số y=f(x)=|2x-1|+2 a,Tính f(-3);f(2/5) b,Tìm x sao cho f(x)=6
$a)$ $f(-3) = |2.(-3)-1|+2 = |(-6)-1|+2 = |(-7)|+2 = 7 + 2 = 9$ $f(\frac{2}{5})=$ $|2.\frac{2}{5}-1|+2=$ $|\frac{4}{5}-1|+2=$ $|\frac{4}{5}-$ $\frac{5}{5}|+2=$ $|\frac{-1}{5}|+2=$ $\frac{1}{5}+2=$ $\frac{1}{5}+$ $\frac{2}{1}=$ $\frac{1}{5}+$ $\frac{10}{5}=$ $\frac{1+10}{5}=$ $\frac{11}{5}$ $b)$ $f(x)=6 ⇔ |2x-1|+2=6$ $⇒ |2x-1|=6-4$ $⇒|2x-1|=4$ $TH1: 2x-1=4$ $⇒2x=4+1$ $2x=5$ $x=$ $\frac{5}{2}$ $TH2: 2x-1=-4$ $⇒2x=(-4)+1$ $2x=-3$ $x=$ $\frac{-3}{2}$ Bình luận
a,
f(-3)= 9
f(2/5)= 11/5
b,
f(x)=6
<=> |2x-1|+2=6
<=> |2x-1|=4
<=> x=5/2 hoặc x= -3/2
$a)$
$f(-3) = |2.(-3)-1|+2 = |(-6)-1|+2 = |(-7)|+2 = 7 + 2 = 9$
$f(\frac{2}{5})=$ $|2.\frac{2}{5}-1|+2=$ $|\frac{4}{5}-1|+2=$ $|\frac{4}{5}-$ $\frac{5}{5}|+2=$ $|\frac{-1}{5}|+2=$ $\frac{1}{5}+2=$ $\frac{1}{5}+$ $\frac{2}{1}=$ $\frac{1}{5}+$ $\frac{10}{5}=$ $\frac{1+10}{5}=$ $\frac{11}{5}$
$b)$
$f(x)=6 ⇔ |2x-1|+2=6$
$⇒ |2x-1|=6-4$
$⇒|2x-1|=4$
$TH1: 2x-1=4$
$⇒2x=4+1$
$2x=5$
$x=$ $\frac{5}{2}$
$TH2: 2x-1=-4$
$⇒2x=(-4)+1$
$2x=-3$
$x=$ $\frac{-3}{2}$