Answer:
Step-by-step explanation:
If you meant to type x+1<21, then we simplify this inequality by subtracting 1 from both sides, ending up with x < 20.
I do not recognize what your "4" represents.
Answer:
x=-8
Step-by-step explanation:

on squaring both sides

either x-2=0 or x+8=0
either x=2 or x=-8
Putting x=2 in original equation, we get

7=7 hence, it is not an extraneous solution
Putting x=-8 in original equation

i.e. 3=-3
Hence, x=-8 is an extraneous solution (since it doesn't satisfy the original equation)
Answer:
14.14
Step-by-step explanation:
10^2 + 10^2 = c^2
100 + 100 = c^2
200 = c^2
c = 14.14
7x7(12+9) to the power of 3
Answer: y= 3x - 
Step-by-step explanation:
Since we know the slope and a set of coordinates we can insert them into the formula y=mx+b and find what b is.
y=mx+b
-1/2=3(2)+b
-1/2=6+b
-1/2-6=6-6+b
-6 1/2=b
Therefore the equation is y=3x - 