Answer:
Answer: To factorize the quadratic expression
x2−9x+20, one must find the two numbers that add together to give 9, and multiply together to give 20. Those two numbers are 4 and 5, which factor into the expression
(x−4)(x−5). The signs are due to the fact that the first sign in the expression is a positive, which tells us that both signs must be the same, and the first sign is a negative, which means that, due to the positive sign in the expression, both signs are negative. To do the opposite, expanding, one must multiply
x by x, to get x2, add together 4 and 5 to get 9, and multiply them to get 20.
Step-by-step explanation:
