Question

Tính: 21. 7² - 11. ( - 7²) + 90. 7² + 51. ( - 10)²

Answer 1

\(21.7^2-11\left(-7\right)^2+90.7^2+51.\left(-10\right)^2\)

\(=21.7^2-11.7^2+90.7^2+51.10^2\)

\(=7^2\left(21-11+90\right)+51.10^2\)

\(=7^2.100+51.100\)

\(=100\left(7^2+51\right)\)

= 100. (49 + 51)

= 100.100

= 10000

Answer 2

21.7 2 − 11 ( − 7 ) 2 + 90.7 2 + 51. ( − 10 ) 2

= 21.7 2 − 11.7 2 + 90.7 2 + 51.10 2

= 7 2 ( 21 − 11 + 90 ) + 51.10 2

= 7 2 .100 + 51.100 = 100 ( 7 2 + 51 )

= 100. (49 + 51)

= 100.100 = 10000