\(x=\frac{2^{2018}+2^{2019}}{2^{2017}+2^{2018}}=\frac{2^{2019}}{2^{2017}}=\frac{2^2}{2}=\frac{4}{2}=2.\)

\(y=\sqrt{10^2-8^2}-\sqrt{3^2+4^2}\)

  \(=\sqrt{100-64}-\sqrt{9+16}\)

  \(=\sqrt{36}-\sqrt{25}\)

\(=6-5=1\)

1-2+3-4+5-6+7-8+...+2017-2018

=-1+-1+-1+...+-1

= -1. 1009

= -1009

#)Giải :

\(1-2+3-4+5-6+...+2017-2018\)

\(=\left(1-2\right)+\left(3-4\right)+\left(5-6\right)+...+\left(2017-2018\right)\)( 1009 cặp )

\(=\left(-1\right)+\left(-1\right)+\left(-1\right)+...+\left(-1\right)\)( 1009 chữ số - 1 )

\(=\left(-1\right).1009\)

\(=-1009\)

a bn tự lm nha mk lm đỡ bn phần b

b=1.99+1.98+3.97+...+98.2+99.1

= 1.99+2.(99-1)+3.(99-2)+...+98.(99-97)+99.(99-98)

= 1.99+2.99-1.2+3.99-2.3+...98.99-97.98+99.99-99.98

=(1.99+2.99+3.99+...+98.99+99.99)-(1.2+2.3+...+98.99)

=99.(1+2+3+...+98+99)-(1.2+2.3+...+98.99)

=99.4950-(1.2+2.3+...+98.99)

=490050-(1.2+2.3+...+98.99)

b=1.2+2.3+...+98.99

3b=1.2.3+2.3.3+...+98.99.3

3b=1.2.3+2.3.(4-1)+...+98.99.(100-97)

3b=1.2.3+2.3.4+2.3.1+...+98.99.100+98.00.97

3b=490050-(98.99.100):3

b=490050-323400

b=166650

tk mk nha

=1.99+2.(99-1)+3.(99-2)+...+98.(99-97)+99(99-98)

=99.(1+2+3+4+...+98+99)-(2+2.3+3.4+...+97.98+98.99)

=99.(1+99).99/2-98.99.100/3

=99.50.99-98.33.100

=490050-323400

=166650