Question

Докажите, что (a^2+1^2)-(a^2-1)^2:a=4

Answer 1

$((a^2+1)^2 - (a^2-1)^2): {a}^{2} =4 \\ (( {a}^{2} + 1 - {a}^{2} + 1)( {a}^{2} + 1 + {a}^{2} - 1) \div {a}^{2} = 4 \\ (2 \times 2 {a}^{2} ) \div {a}^{2} = 4 \\ 4 {a}^{2} \div {a}^{2} = 4 \\ 4 = 4$