It has to be 2.75 as a decimal.
To complete a square for ax²+bx+c, you first make a=1.
in this case, a is already 1
move c to the right side: x²+14x=-47
next, add (1/2 of b)² to both sides, in this case, b=14, half of 14 is 7, so x²+14x+ 7²=-47+7²
the left side is now a perfect square: (x+7)²=2
x+7=√2 or x+7=-√2
x=√2-7, or x=-2-√7
Answer:

Step-by-step explanation:

Answer:
a) 30 cm
b) 20 cm
Step-by-step explanation:
Rectangle B's perimeter is 10+10+5+5 which is 30
Square C's perimeter is 5+5+5+5 which is 20