(1B) The product $(a+b)(c+d)$
Practice
Expand and simplify.
*Write your answers with powers of $x$ in descending order. $\left(\square x^2 \pm \square x \pm \square\right)$
$\left(x+9\right)\left(x-4\right)$
$\left(x+5\right)\left(x+5\right)$
$\left(x-4\right)\left(3+x\right)$
$\left(x-1\right)\left(5-x\right)$
$\left(-6+x\right)\left(x-7\right)$
$\left(3+x\right)\left(x+3\right)$
$\left(6-x\right)\left(6+x\right)$
$\left(7+x\right)\left(4-x\right)$
$\left(7x+2\right)\left(x+6\right)$
$\left(-2x+5\right)\left(5x-7\right)$
$\left(-x+6\right)\left(6+x\right)$
$\left(-3x+4\right)\left(3-7x\right)$
$\left(5+4x\right)\left(-9x+1\right)$
$\left(-3+8x\right)\left(x+7\right)$
$\left(9-x\right)\left(-1+5x\right)$
$\left(3+2x\right)\left(5+4x\right)$