The expression x²-10x-21 is wrong since the product of two negative signs is equal to positive.
Simplifying factors
Quadratic equations are equations that has a leading degree of 2. The standard quadratic equation is given as;
f(x) = ax^2+bx+c
Given the product of the expression below;
f(x) = (x-3)(x-7)
Expand
f(x) = x(x) - 7x - 3x -3(-7)
f(x) = x^2 - 7x - 3x + 21
f(x) = x^2 - 10x + 21
Hence the expression x²-10x-21 is wrong since the product of two negative signs is equal to positive.
Learn more on factoring here: https://brainly.com/question/25829061
#SPJ1
