Question

 

Answer 1

a: \(\left(x-1\right)\left(x+2\right)\)

\(=x^2+2x-x-2\)

\(=x^2+x-2\)

b: \(\left(3+x\right)\left(x+1\right)\)

\(=\left(x+3\right)\left(x+1\right)\)

\(=x^2+x+3x+3\)

\(=x^2+4x+3\)

c: \(\left(3x^2-4\right)\left(x+3\right)\)

\(=3x^2\cdot x+3x^2\cdot3-4\cdot x-4\cdot3\)

\(=3x^3+9x^2-4x-12\)

d: \(\left(3x+5\right)\left(2x-7\right)\)

\(=6x^2-21x+10x-35\)

\(=6x^2-11x-35\)