Question

tính nhanh

a, 69 mũ 2 - 31 mũ 2

b, 1023 mũ 2 - 23 mũ 2

c, 27 mũ 2 + 73 mũ 2 + 54.73

d, 63 mũ 2 + 13 mũ 2 - 26 . 63

e, 25 mũ 2 - 15 mũ 2

i, 87 mũ 2 + 73 mũ 2- 27 mũ 2 - 13 mũ 2

 

Answer 1

a)\(69^2-31^2=\left(69-31\right)\left(69+31\right)=38.100=3800\)

Answer 2

\(1023^2-23^2=\left(1023-23\right)\left(1023+23\right)=1000.1046=1046000\)

Answer 3

\(c,\left(27+73\right)^2-2.27.73+54.73\)

\(100^2-54.73+54.73=10000\)

\(d,\left(63-13\right)^2+2.13.63-26.63=50^2=2500\)

Answer 4

\(e,\left(25-15\right)\left(25+15\right)=10.40=400\)

\(i,\left(87-13\right)\left(87+13\right)+\left(73-27\right)\left(73+27\right)\)

\(\left(87-13\right).100+\left(73-27\right).100\)

\(100\left(87-13+73-27\right)=100.120=12000\)