(√x-√y)•(x+√xy+y)=? (√z+2)•(z-2√z+4)=? (5√t+7)•(25t-35√t+49)=? (√2-2√s)•(2+2√2s+4s)=?

1.) (√x - √y) (x + √xy + y) => x√x + x√y + √xy - x√y - y√x - y√y => x√x + √xy - y√x - y√y 2.) (√z + 2)(z - 2√z + 4) => z√z - 2z + 4√z + 2z - 4√z + 8 => z√z + 8 3.) (5√t + 7)(25t - 35√t + 49) => 125t√t - 175t + 245√t + 175t - 245√t + 343 => 125t√t + 343 4.) (√2 - √2s)(2 + 2√2s + 4s) => 2√2 + 4√s + 4s√2 - 2√2s - 4s - 4s√2s => 2√2 + 4(√s - s) + (4s√2)(1 - √s) => 2[√2 + 2(√s - s) + (2s√2)(1 - √s)]