Question

Factor 5z2 + 19z - 4.

Answer 1

`\huge\boxed{5z^2+19z-4=(z+4)(5z-1)}`

Explanation:

`5z^2+19z-4=5z^2+20z-z-4\\\\\qquad\text{use the distributive property}:a(b+c)=ab+ac\\\\=5z(z+4)-1(z+4)\\\\\qquad\text{use the distributive property}:a(b+c)=ab+ac\\\\=5z\underbrace{(z+4)}_(a)-1\underbrace{(z+4)}_(a)=(z+4)(5z-1)`