What's the square root of -45?

a) -9√5

b) 9i√5

c) -3√5

d) 3i√5

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

One number is 4 less than 3 times a second number. if 3 more than two times the first number is decreased by 2 times the second number, the result is 11. use the substitution method. what is the first number?

The ratio of the perimeters of two similar triangles is 4: 3. what are the areas of these triangles if the sum of their areas is 130cm2?