When Joanne checked her Work by substituting the value of the variable back into the equation she got an answer of 12.34 equals 12.33 explain why Joanne could have gotten the answer correct even though she did not get a true statement when she checked her work

Joanne could have rounded her answer to a specific decimal place, rather than using the exact answer. If you use a rounded answer to verify your solution, you may get a statement that is not exactly equal. The numbers, 12.34 and 12.33 are very close to each other, so Joanne can assume she solved the multistep equation correctly.

Step-by-step explanation:

Facts

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240