Let the x represent the unknown number.
"2 times a number" is 2x
"The sum of 2 times a number and 11" is 2x + 11
"The sum of 2 times a number and 11 is -7" is 2x + 11 = -7
Now we solve the equation for x to find the unknown number.
2x + 11 = -7
Subtract 11 from both sides.
2x = -18
Divide both sides by 2.
x = -9
Answer: The number is -9.
Check: 2 times -9 = -18
-18 + 11 = -7
The answer is correct.
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3c/3 = 15/3 Divide both sides by 3
15/3 = 5 Simplify 15/3
c = 5
Hope this helps!
Answer:
Step-by-step explanation:
We expect the equation for y to be quadratic. Since the table is obviously symmetrical about x=3, we can start with the vertex form ...
y = a(x -3)² +b
Filling in the values from the first two table points, we get
For (x, y) = (0, 6):
6 = a(0 -3)² + b ⇒ 9a +b = 6
For (x, y) = (2, 22):
22 = a(2-3)² +b ⇒ a +b = 22
Subtracting the second equation from the first gives ...
(9a +b) -(a +b) = (6) -(22)
8a = -16 . . . . . . collect terms
a = -2 . . . . . . . . divide by 8
The second equation above tells us ...
b = 22 -a = 22 -(-2) = 24
So, our equation for y is ...
y = -2(x -3)² +24
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The value of y for x=5 is ...
y = -2(5 -3)² +24 = 16
The height of the ball after 5 seconds is 16 feet.