Verified answer

g) (a+3b)(6a-2b)+3ab+2(3a)²=6a²+18ab-2ab-6b²+3ab+2*9a²=

=6a²+18ab-2ab-6b²+3ab+18a²=24a²+19ab-6b².

h) (2a+4b)²+3*(-5b)²-7a*4b=4a²+16ab+16b²+3*25b²-28ab=

=4a²+16ab+16b²+75b²-28ab=4a²-12ab+91b².

i) (5a-b)(5a+b)+(-4b)²*3=25a²-b²+16b²*3=25a²-b²+48b²=25a²+47b².

j) (3a+8b)(4a+5b)-(b-2a)²=12a²+32ab+15ab+40b²-b²+4ab-4a²=8a²+51ab+39b².