Answer:
x = 9, 8
Step-by-step explanation:
1) To find all values of x by factoring, move all the terms to one side, setting them to zero. So, add both sides by -3x to move the term:
[tex]x^2-20x + 72 = -3x\\x^2 -17x+72 = 0[/tex]
2) Now, factor the expression. The product of -8 and -9 equals 72, and adding the two numbers together equals -17. So, the factored expression must be (x-9) (x-8):
[tex]x^2-17x + 72 = 0 \\(x-9)(x-8)= 0[/tex]
3) Look at the expressions in the parentheses. Whatever values of x that makes each expression equal 0 will be the answer. Thus, x must equal 9 and 8.
