Answer:
Hello,
Answer b: 25
Step-by-step explanation:
[tex]x^4+6x^3+19x^2+30x+a=(x^2+bx+c)^2\\=x^4+2bx^3+b^2x^2+c^2+2cx^2+2bcx\\\\\Longrightarrow\ \left\{\begin{array}{ccc}2b&=&6\\b^2+2c&=&19\\2bc&=&30\\a&=&c^2\\\end{array}\right.\\\\\Longrightarrow\ \left\{\begin{array}{ccc}b&=&3\\c&=&\dfrac{30}{2*3}=5\\9+2*5&=&19\\a&=&5^2\\\end{array}\right.[/tex]
We must add 25
Answer b) 25
