Iam supposed to show that 4 − (x + 2)2 = −x(x + 4) by factorising the left-hand side. but i don't understand how to do it. can someone explain it to me?

Carley bought a jacket that was discounted 10% off the original price. the expression below represents the discounted price in dollars, based on x, the original price of the jacket.

Mallory has been offers two different jobs. she can baby sit for 6 hours a week and get $8.50 an hour. or she can work at the library for 14 hours a week and make $5.50 an hour. which job will allow her to save the most money after 6weeks?

Simplify each expression for 18, 20, and 21