a)(2x+5)(x-3)=2x²-6x+5x-15=2x²-x-15
b)(1-2x)(3x+4)=3x+4-6x²-8x=-6x²-5x+4
c)(a+3)(5a-2)=5a²-2a+15a-6=5a²+13a-6
d)(x+y)(2x-y)=2x²-xy+2xy-y²=2x²+xy-y²
e)(2x-7y)(3y+5x)=6xy+10x²-21y²-35xy=10x²-21y²-29xy
f)(3m+2n)(3m-2n)=9m²-6mn+6mn-4n²=9m²-4n²
g)(m+n)(m²+n²)=m³+n²m+m²n+n³