A weightlifter uses a total of 12 plates to add 260 pounds to a bar. He uses 45-pound plates and 10-pond plates. Write and solve a system of equations to find the number x of 45-pond and the number y of 10-ponds plates he uses.

45 pound plate = 4

10 pound plate = 8

Step-by-step explanation:

x = 45 pound plate

y = 10 pound plate

x + y = 12 - - - (1)

45x + 10y = 260 - - (2)

x = 12 - y

45(12 - y) + 10y = 260

540 - 45y + 10y = 260

540 - 35y = 260

-35y = 260 - 540

-35y = - 280

y = 280 / 35

y = 8

x = 12 - y

x = 12 - 8

x = 4

center (1,3) with radius 6

step-by-step explanation:

we must complete the square to find the center and radius of the circle.

first make sure the x and y squared terms have 1 as their coefficients. we also make sure x and y terms together.

we now create space between the x and y terms with parenthesis.

we complete the square by taking the middle terms -2x and the -6y - divide each and square them.

we add the squares to both sides.

simplify.

and write the quadratics in factored form.

the center is (h,k) or (1,3). the radius is the square root of 36 which is 6.

363 square inches

step-by-step explanation:

surface area of a pyramid is b + 1/2ph

b is the area of the base: 11 x 11 = 121

p is the perimeter of the base: 11 + 11 + 11 + 11 = 44

h is the height of the pyramid: 11

121 + 1/2(44)(11)

121 + 242

363