91Ó°ÊÓ

Round your answer to the nearest tenth. A ball is thrown upward from the top of a building so that its height \(h\) (in feet) above the ground \(t\) seconds after it is thrown is given by $$ h=120+40 t-16 t^{2} $$ In how many seconds is the ball \(140 \mathrm{ft}\) above the ground?

Round your answer to the nearest tenth. A ball is thrown downward from the top of a cliff 1280 ft high so that the distance \(d\) the ball has fallen (in feet) \(t\) seconds after it is thrown is given by $$ d=75 t+16 t^{2} $$ How many seconds does it take for the ball to hit the ground?

In Exercises \(1-64\), solve each of the given equations. If the equation is quadratic, use the factoring or square root method. If the equation has no real solutions, say so. $$\left(x-\frac{3}{7}\right)^{2}=\frac{5}{49}$$

Multiply and simplify. $$(x+8)^{2}$$

Simplify as completely as possible. (Assume \(x \geq 0 .)\) $$\frac{10-\sqrt{20}}{6}$$

Multiply and simplify. $$(x+5)(x-5)$$

In Exercises \(1-64\), solve each of the given equations. If the equation is quadratic, use the factoring or square root method. If the equation has no real solutions, say so. $$\left(y-\frac{1}{2}\right)^{2}=\frac{2}{3}$$

Solve the following problem algebraically. Be sure to indicate what the variable represents. Yvonne can assemble a 1000 -piece jigsaw puzzle in 8 hours, while Bill can assemble the same puzzle in 10 hours. Bill starts working on the puzzle alone and quits after 3 hours. How long will it take Yvonne to finish the puzzle on her own?

In Exercises \(1-64\), solve each of the given equations. If the equation is quadratic, use the factoring or square root method. If the equation has no real solutions, say so. $$\left(x+\frac{1}{3}\right)^{2}=\frac{3}{5}$$

Multiply and simplify. $$(x+8)(x-8)$$