Ответ:

5a²+7b²+8аb

Объяснение:

(f-c)*(f+c)=f²-c²

(f+c)²=f²+2fc+c²

(а+4b)²+(2a-3b)(2a+3b)=а²+8аb+16b²+4a²-9b²=5a²+7b²+8аb

Verified answer

[tex]\displaystyle\bf\\(a+4b)^{2}+(2a-3b)(2a+3b)=a^{2} +2\cdot a\cdot 4b+(4b)^{2} +(2a)^{2} -(3b)^{2} =\\\\\\=a^{2} +8ab+16b^{2} +4a^{2} -9b^{2} =5a^{2} +8ab+7b^{2}[/tex]