Find the mistake and correct. 10x+7 y = -!!
7x-2y = -1
STEP #1 2 (10x + 3y =-11)
7T-7x-2y=-1)
STEP #23 20x+14y = - 22
-49x - 4y = -1
- 29x = -23
-29
-29
or x = 0.79
x = 2
10 (0.79)+7y = -11
STEP 3
7,9+7y=-
-7.9
+y=-11.9
# 7
y=-1.7
같
STEP Ч:
60.79,-1.7)

x-3y=4

step-by-step e

(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