Jorge has only dimes and nickels in his piggy bank. He has a total of 77 coins. The value of the coins is $6.95. Write and solve
a system that can be used to determine how many dimes and how many nickels he has.
1 answer:
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Answer:
Step-by-step explanation:
This is a parabola since a quadratic is a parabola. The standard form for a parabola is y = ax² + bx + c
but before we do that, we will use the vertex form, since it will make our work easier at the beginning.
First and foremost, when we plot the vertex and the given point, the vertex is higher up than is the point; that means that this parabola opens upside down, and its vertex form will be
y=-|a|(x - h)² + k
The absolute value is out in front of the a, so we know that the value of a is positive, but the quadratic itself is negative (upside down) and we will find that math takes care of that negative that needs to be out front. So we need to solve for a by filling in the x, y, h, and k values from the point and the vertex: x = -7, y = 0, h = -3, k = 4
0 = a(-7 - (-3))² + 4 and
0 = a(-7 + 3)² + 4 and
0 = a(-4)² + 4 and
0 = a(16) + 4 and
0 = 16a + 4 and
-4 = 16a so
Now that we know a, we can plug it back into the vertex form and then put it into standard form from there.
Now we will FOIL out what's inside the parenthesis to get
Simplify by distributing the -1/4 into the parenthesis:
Combine like terms to get
And there you go!