1. (15+k²)²
2. (m²-3n)²
3. (m⁴-n³)²
4.
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1. (15+k^2)^2
225+30k^2+k^4
k^4+30k^2+225
2.(m^2-3n)^2
(m^2)^2-2m^2•3n+(3n)^2
m^4-6m^2n+9n^2
3. (m^4-n^3)^2
(m^4)^2-2m^4n^3+(n^3)^2
m^8-2m^4n^3+n^6
4. (5a^4-2a^7)^2
25a^8-20a^11+4a^14
4a^14-20a^11+25a^8

1) (15+k^2)^2=225+30k^2+k^4=k^4+30k^2+225
2) (m^2-3n)^2=(m^2)^2-2m^2*3n+(3n)^2=m^4-6m^2n+9n^2
3) (m^4-n^3)^2=(m^4)^2-2m^4n^3+(n^3)^2=m^8-2m^4n^3+n^6
4) (5a^4-2a^7)^2=25a^8-20a^11+4a^14=4a^14-20a^11+25a^8