Answer:
12.57
Step-by-step explanation:
the formula for the area of a circle is 
the diameter is 2 times the radius, so dividing it by 2 gives you a radius of 2
substitute the 2 for the r in the formula and solve

4
≈12.57
5. y = -3 x - 8
6. y = - 1/2 x + 1
Answer:
9.3 × 10⁷ - 3.4 × 10⁶ = 89 600 000
Which is 8.96*10^7 in scientific notation
Hope this helps you