Question

5 tính nhanh

a) 301²

b) 499²

c)68.72

Answer 1

a, \(\left(301\right)^2=\left(300+1\right)^2=300^2+2.300.1+1^2\)

=90000+6000+1=90601

b,\(499^2=\left(500-1\right)^2=500^2-2.500.1+1^2\)

=10000-10000+1=1

Answer 2

a) 301² = ( 300 + 1 )² = 300² + 2.300.1 + 1² = 90601

b) 499² = ( 500 - 1 )² = 500² - 2.500.1 + 1² = 249001

c) 68.72 = ( 70 - 2). ( 70 + 2) = 70² - 4² = 4900 - 16 = 4884

Answer 3

a) 90601

b)249001

c)4896

Answer 4

a) 301² = (300 + 1)² = 300² + 2.300.1 + 1² = 90000 + 600+ 1 = 90601

b) 499² = (500 - 1)² = 500² - 2.500.1 + 1² = 250000 - 1000 + 1 = 249001

c) 68.72 = (70 - 2)(70 + 2) = 70² - 2² = 4900 - 4 = 4896