What percent of 12 is 15?
2 answers:
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Answer:
<h2>y = -2x + -3</h2>Step-by-step explanation:
Slope-intercept form is y = mx + b
"m" is the slope, how steep the line is.
"b" is the y-intercept, where to graph hits the y-axis.
Check the scale for this grid. Since there are "1" written on the first box after the middle, <u>one square = one unit</u>.
To find "m", use between the two dotted points on the graph. The first point is always on the left.
<u>"Rise" means how many squares above</u> the first point the second point is.
Since the second point is below the first point, the number is negative.
<u>"Run" means how many squares to the right</u> the second point is.
To find "b", look at where the graph it touching the y-axis.
The y-axis is the vertical line (going from top to bottom).
Count the number of squares from the grid's middle to the graph line.
There are 3 squares.
Since the graph touches below the origin, this is a negative number.
b = -3
In the boxes, you put negative two (-2) and negative three (-3).
* Usually we would simplify the equation to y = -2x - 3.
A second degree polynomial function has the general form:
, where 
.
The leading coefficient is a, so we have a=-1.
5 is a double root means that :
i) f(5)=0,
ii) the discriminant D is 0, where
.
Substituting x=5, we have
f(5)=a(5)^2+b(5)+c,
and since f(5)=0, and a is -1 we have:
0=-25+5b+c
thus c=25-5b.
By ii)
.
Substituting a with -1 and c with 25-5b we have:
Finally we find c: c=25-5b=25-50=-25
Thus the function is
Remark: It is also possible to solve the problem by considering the form
directly.
In general, if a quadratic function has leading coefficient a, and has a root r of multiplicity 2, then its form is
The leading coefficient is a, so we have a=-1.
5 is a double root means that :
i) f(5)=0,
ii) the discriminant D is 0, where
Substituting x=5, we have
f(5)=a(5)^2+b(5)+c,
and since f(5)=0, and a is -1 we have:
0=-25+5b+c
thus c=25-5b.
By ii)
Substituting a with -1 and c with 25-5b we have:
Finally we find c: c=25-5b=25-50=-25
Thus the function is
Remark: It is also possible to solve the problem by considering the form
In general, if a quadratic function has leading coefficient a, and has a root r of multiplicity 2, then its form is