Question

\(87^2\)+\(73^2\)-\(27^2\)-\(13^2\)

Answer 1

\(87^2+73^2-27^2-13^2\)

\(=87^2-13^2+73^2-27^2\)

\(=\left(87^2-13^2\right)+\left(73^2-27^2\right)\)

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

\(=74\cdot100+46\cdot100\)

\(=7400-4600\)

\(=2800\)