Chứng minh rằng : Nếu \(\frac{a+2018}{a-2018}\)= \(\frac{b+2019}{b-2019}\)thì \(\frac{a}{2018}\)= \(\frac{b}{2019}\)
Cho A=\(\frac{2018^{2018}}{2019^{2019}}\) Và B=\(\frac{2018^{2018}+2018}{2019^{2019}+2019}\) So sánh A và B
a) Cho các số dương a,b,c,d; c khác d và \(\frac{a}{b}\)=\(\frac{c}{d}\). Chứng minh rằng : \(\frac{\left(a^{2018}+b^{2018}\right)^{2019}}{\left(c^{2018}+d^{2018}\right)^{2019}}\)=\(\frac{\left(a^{2019}-b^{2019}\right)^{2018}}{\left(c^{2019}-d^{2019}\right)^{2018}}\)
b) Cho biết |3x + 2y| + |5z - 7x| + \(\left(xy+yz+xz-500\right)^{2022}\)= 0 . Tính giá trị : \(A=\left(3x-y-z\right)^{2021}\)
Các bạn giải giúp mik nhé. Mik cần gấp lắm. Ai giải trc mik sẽ tick cho
So sánh hai biểu thức A và B biết rằng :
\(A=\frac{2018}{2019}+\frac{2019}{2020}\) và \(B=\frac{2018+2019}{2019+2020}\)
\(B=\frac{2018}{2019+2020}+\frac{2019}{2019+2020}< \frac{2018}{2019}+\frac{2019}{2020}=A\)
\(\Rightarrow B< A\)
Cho \(a,b,c\ne0\)có \(a+b=c+\frac{1}{2018}\)
\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}+2018\)
Chứng minh \(P=a^{2019}+b^{2019}+c^{2019}\)
cho A=\(\frac{2018^{2019}+1}{2018^{2019}-2017}\)và B=\(\frac{2018^{2019}+2}{2018^{2019}-2016}\)
So sánh A và B
Có: \(A=\frac{2018^{2019}+1}{2018^{2019}-2017}=\frac{2018^{2019}+1-2018+2018}{2018^{2019}-2017}=\frac{2018^{2019}-2017+2018}{2018^{2019}-2017}=1+\frac{2018}{2018^{2019}-2017}\)
\(B=\frac{2018^{2019}+2}{2018^{2019}-2016}=\frac{2018^{2019}+2-2018+2018}{2018^{2019}-2016}=\frac{2018^{2019}-2016+2018}{2018^{2019}-2016}=1+\frac{2018}{2018^{2019}-2016}\)
Mà: \(\frac{2018}{2018^{2019}-2017}>\frac{2018}{2018^{2019}-2016}\)
\(\Rightarrow1+\frac{2018}{2018^{2019}-2017}>1+\frac{2018}{2018^{2019}-2016}\\ \Rightarrow A>B\)
CMR: nếu có \(\frac{a+2019}{a-2019}=\frac{b+2019}{b-2019}\)
thì \(\frac{a}{b}=\frac{2019}{2018}\)
\(\frac{a+2019}{a-2019}=\frac{b+2019}{b-2019}\Leftrightarrow\left(a+2019\right).\left(b-2019\right)=\left(a-2019\right).\left(b+2019\right)\)
\(\Rightarrow ab-2019a+2019b-2019^2=ab+2019a-2019b-2019^2\)
\(\Leftrightarrow-2019a+2019b=2019a-2019b\Rightarrow2.2019b=2.2019a\Rightarrow2019a=2019b\Rightarrow\frac{a}{b}=\frac{2019}{2019}\)(vì a,b khác 0)
t chắc rằng đề lỗi =.=' có gì bỏ qua
chứng minh rằng biểu thức \(B=\sqrt{1+2018^2+\frac{2018^2}{2019^2}}+\frac{2018}{2019}\) có giá trị là 1 số tự nhiên
\(B=\sqrt{\frac{2019^2}{2019^2}+2018^2+\frac{2018^2}{2019^2}}+\frac{2018}{2019}\)
\(B=\sqrt{\frac{\left(2018+1\right)^2}{2019^2}+\frac{2018^2}{2019^2}+2018^2}+\frac{2018}{2019}\)
\(B=\sqrt{\frac{1}{2019^2}+\frac{2018^2+2.2018+2018^2}{2019^2}+2018^2}+\frac{2018}{2019}\)
\(B=\sqrt{\frac{1}{2019^2}+2.2018.\frac{1}{2019}+2018^2}+\frac{2018}{2019}\)
\(B=\sqrt{\left(\frac{1}{2019}+2018\right)^2}+\frac{2018}{2019}\)
\(B=\frac{1}{2019}+2018+\frac{2018}{2019}=2019\) là một số tự nhiên
\(B=\sqrt{1+2018^2+\frac{2018^2}{2019^2}}+\frac{2018}{2019}\)
\(B=\sqrt{1^2+2018^2+\left(-\frac{2018}{2019}\right)^2}+\frac{2018}{2019}\)
\(B=\sqrt{\left(1+2018-\frac{2018}{2019}\right)^2+2.\frac{2018}{2019}+2.\frac{2018^2}{2019}-2.2018}\)\(+\frac{2018}{2019}\)
\(B=\sqrt{\left(1+2018-\frac{2018}{2019}\right)^2+2\left(\frac{2018+2018.2018-2018.2019}{2019}\right)}\)\(+\frac{2018}{2019}\)
\(B=\sqrt{\left(1+2018-\frac{2018}{2019}\right)^2}+\frac{2018}{2019}\)
\(B=1+2018-\frac{2018}{2019}+\frac{2018}{2019}=2019\)
Vậy B có giá trị là 1 số tự nhiên.
A = \(\frac{2016}{2017}+\frac{2017}{2018}+\frac{2018}{2019}\)và B = \(\frac{2016+2017+2018}{2017+2018+2019}\)
\(A=\frac{2016}{2017}+\frac{2017}{2018}+\frac{2018}{2019}\)
\(\Rightarrow A=(1-\frac{1}{2017})+(1-\frac{1}{2018})+(1-\frac{1}{2019})\)
\(\Rightarrow A=3-\left(\frac{1}{2017}+\frac{1}{2018}+\frac{1}{2019}\right)\)
\(\left(\frac{1}{2017}+\frac{1}{2018}+\frac{1}{2019}\right)\)<\(\frac{3}{2017}\)<\(1\)
\(\Rightarrow A\)>\(3-1=2\)
\(B=\frac{2016+2017+2018}{2017+2018+2019}\)
\(\Rightarrow B=1-\frac{3}{6054}\)
\(\Rightarrow B=1-\frac{1}{2018}\)
\(B\)<\(1\);\(A\)>\(2\)
\(\Rightarrow A\)>\(B\)
So sánh A và B:
\(A=\frac{2018^2}{2^{2018}+3^{2019}}+\frac{3^{2019}}{3^{2019}+5^{2020}}+\frac{5^{2020}}{5^{2020}+2^{2018}}\)
\(B=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{2019.2020}\)
B= 1/1.2+1/2.3+...+1/2019.2020
B=1/1-1/2+1/2-1/3+...+1/2019-1/2020
B=1-1/2020=2020/2020-1/2020=2019/2020