Bài 1:
a,$\frac{2}{3}$-( -$\frac{5}{7}$+ $\frac{2}{3}$)=$\frac{2}{3}$-(-$\frac{1}{21}$)= $\frac{5}{7}$
b,$\frac{-2}{15}$+ $\frac{-11}{5}$+1= $\frac{-7}{3}$+1=$\frac{-4}{3}$
c,$\frac{5}{9}$.$\frac{8}{11}$+$\frac{5}{9}$.$\frac{9}{11}$-$\frac{5}{9}$.$\frac{6}{11}$=$\frac{5}{9}$($\frac{8}{11}$+$\frac{9}{11}$-$\frac{6}{11}$)=$\frac{5}{9}$.1= $\frac{5}{9}$
Bài 2:
a,x-$\frac{1}{4}$=$\frac{5}{8}$.$\frac{2}{3}$ b,|x-$\frac{1}{2}$|= $\frac{3}{2}$
⇒x-$\frac{1}{4}$=$\frac{5}{12}$ TH1:x-$\frac{1}{2}$= $\frac{3}{2}$
⇒ x =$\frac{2}{3}$ x = $\frac{3}{2}$+$\frac{1}{2}$
Vậy x =$\frac{2}{3}$ x =2
TH2:x-$\frac{1}{2}$=-$\frac{3}{2}$
x =-$\frac{3}{2}$+$\frac{1}{2}$
x =-1
Vậy x ∈ { 2; -1}
Bài 3:
A=$\frac{4^{3}.5^{2}+16.125}{2^{3}.5^{2}}$
=$\frac{4^{3}.5^{2}+4^{2}.5^{3}}{2^{3}.5^{2}}$
=$\frac{2^{6}.5^{2}+2^{4}.5^{3}}{2^{3}.5^{2}}$
=$\frac{2^{3}.2^{3}.5^{2}+2^{3}.2.5^{2}.5}{2^{3}.5^{2}}$
=$\frac{2^{3}.5^{2}(2^{3}+2.5)}{2^{3}.5^{2}}$
=$2^{3}$+2.5
=8+10
=18
CHÚC BẠN HỌC TỐT~
Cho mik câu tl hay nhất được ko zị ^^
