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