Answer:
15x5−x4−2x3+21x2+7x
Step-by-step explanation:
=(3x2+x)(5x3+−2x2+7)
=(3x2)(5x3)+(3x2)(−2x2)+(3x2)(7)+(x)(5x3)+(x)(−2x2)+(x)(7)
=15x5−6x4+21x2+5x4−2x3+7x
=15x5−x4−2x3+21x2+7x
