1) (a+b)^2 = a^2 + 2ab + b^2= 7^2 + 2×7×5 + 5^2 = 144
2) (a+b)(a-b) = a^2 - b^2 = 7^2 -5^2 = 24
3) (a-b)^2 = a^2 - 2ab + b^2 = 7^2 -2×7×5 + 5^2 = 4
4) a^2 + 2ab + b^2 = 7^2 + 2×7×5 + 5^2 = 144
5) a^2 - b^2 = 7^2 - 5^2 = 24
6) a^2 + b^2 - 2ab = 7^2 + 5^2 - 2×7×5 = 4