Question

Bài 3

a) 21.7²-11.7²+90.7²+49.125.16

Answer 1

a) 21.7²-11.7²+90.7²+49.125.16

=21.7²-11.7²+90.7²+7².2000

=7².(21-11+90+2000)

=7².2100

=49.2100

=102900

Answer 2

a) \(21\cdot7^2-11\cdot7^2+90\cdot7^2+7^2\cdot125\cdot16=7^2\cdot\left(21-11+90+125\cdot16\right)=7^2\cdot2100=102900\)

Answer 3

\(21.7^2-11.7^2+90.7^2+49.125.16\)

=\(21.7^2-11.7^2+90.7^2+7^2.2000\)

=\(7^2.\left(21-11+90+2000\right)\)

=\(7^2.2100\)

=\(102900\)