Do trong nguyên tử M số hạt mang điện lớn hơn số hạt không mang điện là 10 hạt

 (p+e) - n = 10

 2p - n = 10 (vì nguyên tử trung hòa về điện)

Ta được

2p - (p+1) = 10 

= 2p - p - 1 =10

= p = 11

= e = 11 (hạt)

a)

=\(\dfrac{7}{5}\)x\(\dfrac{15}{49}\)-(\(\dfrac{12}{15}\)+\(\dfrac{10}{15}\)):\(\dfrac{11}{5}\)

=\(\dfrac{3}{7}\)-\(\dfrac{22}{15}\):\(\dfrac{11}{5}\)

=\(\dfrac{3}{7}\)-\(\dfrac{22}{15}\)x\(\dfrac{5}{11}\)

=\(\dfrac{3}{7}\)-\(\dfrac{2}{3}\)

=\(\dfrac{9}{21}\)-\(\dfrac{14}{21}\)

=\(\dfrac{-5}{21}\)

b)

=\(\dfrac{-32}{10}\)x\(\dfrac{-15}{64}\)+(\(\dfrac{8}{10}\)-\(\dfrac{34}{15}\)):\(\dfrac{11}{3}\)

=\(\dfrac{3}{4}\)+\(\dfrac{-22}{15}\):\(\dfrac{11}{3}\)

=\(\dfrac{3}{4}\)+\(\dfrac{-22}{15}\)x\(\dfrac{3}{11}\)

=\(\dfrac{3}{4}\)+\(\dfrac{-2}{5}\)

=\(\dfrac{15}{20}\)-\(\dfrac{8}{20}\)

=\(\dfrac{7}{20}\)

à mik chũ xem hết xl ạ

ok bn

vừa trl xong xem lại sao bị looix nhỉ

399 x 45 + 55 x 399 / 1995 x 1996 - 1991 x 1995

= 399 x (45 + 55) / 1995 x (1996 - 1991)

= 399 x 100 / 1995 x 5=399 x 100/ 399 x 5 x 5

= 399 x 100/399 x 25

=100/25 = 4

=(x²)³+(y²)³

=(x²+y²)(x⁴-x²y²+y⁴)

có

\(\Rightarrow\)Ko đăng lại