28.6. Раскройте скобки: а) (8x + 3y)²; б) (9p − 2q)²; в) (6m − 4n)²; г) (10z + 3t)².

1. \((8x+3y)^2=(8x)^2+2\cdot8x\cdot3y+(3y)^2=64x^2+48xy+9y^2\).
2. \((9p-2q)^2=(9p)^2-2\cdot9p\cdot2q+(2q)^2=81p^2-36pq+4q^2\).
3. \((6m-4n)^2=(6m)^2-2\cdot6m\cdot4n+(4n)^2=36m^2-48mn+16n^2\).
4. \((10z+3t)^2=(10z)^2+2\cdot10z\cdot3t+(3t)^2=100z^2+60zt+9t^2\).

Ответ: а) \(64x^2+48xy+9y^2\); б) \(81p^2-36pq+4q^2\); в) \(36m^2-48mn+16n^2\); г) \(100z^2+60zt+9t^2\).