Answer:
If you look over the steps you can see that until 4x + x + 3 = 18, evertything is dandy. But the step after that 4x + x =21 seems a bit fishy.
Think about it they subtract 3 from both sides so the first side is correct
4x + x, but they added 3 to the other side:

not
4x+x = 21
Then we solve for 4x + x = 15

To solve for y we use :
y = x+3
y = 3+3 = 6
so (3,6) is the right answer
It’s 3!! I checked on a calculator :)
It is an acute triangle since all the sides are less than 90 degrees (it's also equilateral)
Answer:
A. 4x²+20x+25
Step-by-step explanation:
Because of PEMDAS, you calculate the value inside of the parenthesis first, so you expand [2x+1-(4x+6)]:
2x+1-4x-6 = -2x-5.
Then apply the exponent:
(-2x-5)² = (-2x-5)(-2x-5) = 4x²+10x+10x+25 = 4x²+20x+25