Answer:
he invented the point
he was a German mathematician
he Hilbert's improvements to geometry are still used in textbooks today
he developed Hilbert's axioms
Step-by-step explanation:
<span>q =r/2(s+t) for t
</span><span>2q =r(s+t)
2q = rs + rt
rt = 2q - rs
t = 2q/r - s
hope it helps</span>
Since x is the number of seconds it took the rock to hit the water, x is the value that we are looking for. When the rock hits the water, it's height is 0, therefore, f(x) = 0. So, we can set the expression on the right equal to 0, and solve for 0. Let's do just that:

We can divide by -16, nothing will happen because 0 divided by anything is 0:

To factor any trinomial in standard form (given below), we must find two numbers that add to "b" and multiply to "c":

So, for this specific question, let's find two numbers that add to -8 and multiply to 9. These are clearly 9 and -1. We can write it in this way now:

Both answers would be valid, but there can't be negative time, so your answer is
"It takes 9 seconds for the rock to reach the water."
Answer: 2/3
Step-by-step explanation: In this problem, we have 8/15 ÷ 4/5. Dividing by a fraction is the same as multiplying by its reciprocal. In other words, we can change the division sign to multiplication and flip the second fraction.
8/15 ÷ 4/5 can be rewritten as 8/15 × 5/4
Now, we are simply multiplying fractions so we multiply across the numerators and multiply across the denominators.
8/15 × 5/4 = 40/60 = 2/3