Solution - Quadratic equations
Step by Step Solution
Reformatting the input :
Changes made to your input should not affect the solution:
(1): "x2" was replaced by "x^2".
Step by step solution :
Step 1 :
Equation at the end of step 1 :
((0 - (2•137x2)) - 617x) + 702 = 0
Step 2 :
Step 3 :
Pulling out like terms :
3.1 Pull out like factors :
-274x2 - 617x + 702 = -1 • (274x2 + 617x - 702)
Trying to factor by splitting the middle term
3.2 Factoring 274x2 + 617x - 702
The first term is, 274x2 its coefficient is 274 .
The middle term is, +617x its coefficient is 617 .
The last term, "the constant", is -702
Step-1 : Multiply the coefficient of the first term by the constant 274 • -702 = -192348
Step-2 : Find two factors of -192348 whose sum equals the coefficient of the middle term, which is 617 .
-192348 | + | 1 | = | -192347 | ||
-96174 | + | 2 | = | -96172 | ||
-64116 | + | 3 | = | -64113 | ||
-48087 | + | 4 | = | -48083 | ||
-32058 | + | 6 | = | -32052 | ||
-21372 | + | 9 | = | -21363 |
For tidiness, printing of 42 lines which failed to find two such factors, was suppressed
Observation : No two such factors can be found !!
Conclusion : Trinomial can not be factored
Equation at the end of step 3 :
-274x2 - 617x + 702 = 0
Step 4 :
Parabola, Finding the Vertex :
4.1 Find the Vertex of y = -274x2-617x+702
Parabolas have a highest or a lowest point called the Vertex . Our parabola opens down and accordingly has a highest point (AKA absolute maximum) . We know this even before plotting "y" because the coefficient of the first term, -274 , is negative (smaller than zero).
Each parabola has a vertical line of symmetry that passes through its vertex. Because of this symmetry, the line of symmetry would, for example, pass through the midpoint of the two x -intercepts (roots or solutions) of the parabola. That is, if the parabola has indeed two real solutions.
Parabolas can model many real life situations, such as the height above ground, of an object thrown upward, after some period of time. The vertex of the parabola can provide us with information, such as the maximum height that object, thrown upwards, can reach. For this reason we want to be able to find the coordinates of the vertex.
For any parabola,Ax2+Bx+C,the x -coordinate of the vertex is given by -B/(2A) . In our case the x coordinate is -1.1259
Plugging into the parabola formula -1.1259 for x we can calculate the y -coordinate :
y = -274.0 * -1.13 * -1.13 - 617.0 * -1.13 + 702.0
or y = 1049.344
Parabola, Graphing Vertex and X-Intercepts :
Root plot for : y = -274x2-617x+702
Axis of Symmetry (dashed) {x}={-1.13}
Vertex at {x,y} = {-1.13,1049.34}
x -Intercepts (Roots) :
Root 1 at {x,y} = { 0.83, 0.00}
Root 2 at {x,y} = {-3.08, 0.00}
Solve Quadratic Equation by Completing The Square
4.2 Solving -274x2-617x+702 = 0 by Completing The Square .
Multiply both sides of the equation by (-1) to obtain positive coefficient for the first term:
274x2+617x-702 = 0 Divide both sides of the equation by 274 to have 1 as the coefficient of the first term :
x2+(617/274)x-(351/137) = 0
Add 351/137 to both side of the equation :
x2+(617/274)x = 351/137
Now the clever bit: Take the coefficient of x , which is 617/274 , divide by two, giving 617/548 , and finally square it giving 617/548
Add 617/548 to both sides of the equation :
On the right hand side we have :
351/137 + 617/548 The common denominator of the two fractions is 548 Adding (1404/548)+(617/548) gives 2021/548
So adding to both sides we finally get :
x2+(617/274)x+(617/548) = 2021/548
Adding 617/548 has completed the left hand side into a perfect square :
x2+(617/274)x+(617/548) =
(x+(617/548)) • (x+(617/548)) =
(x+(617/548))2
Things which are equal to the same thing are also equal to one another. Since
x2+(617/274)x+(617/548) = 2021/548 and
x2+(617/274)x+(617/548) = (x+(617/548))2
then, according to the law of transitivity,
(x+(617/548))2 = 2021/548
We'll refer to this Equation as Eq. #4.2.1
The Square Root Principle says that When two things are equal, their square roots are equal.
Note that the square root of
(x+(617/548))2 is
(x+(617/548))2/2 =
(x+(617/548))1 =
x+(617/548)
Now, applying the Square Root Principle to Eq. #4.2.1 we get:
x+(617/548) = √ 2021/548
Subtract 617/548 from both sides to obtain:
x = -617/548 + √ 2021/548
Since a square root has two values, one positive and the other negative
x2 + (617/274)x - (351/137) = 0
has two solutions:
x = -617/548 + √ 2021/548
or
x = -617/548 - √ 2021/548
Note that √ 2021/548 can be written as
√ 2021 / √ 548
Solve Quadratic Equation using the Quadratic Formula
4.3 Solving -274x2-617x+702 = 0 by the Quadratic Formula .
According to the Quadratic Formula, x , the solution for Ax2+Bx+C = 0 , where A, B and C are numbers, often called coefficients, is given by :
- B ± √ B2-4AC
x = ————————
2A
In our case, A = -274
B = -617
C = 702
Accordingly, B2 - 4AC =
380689 - (-769392) =
1150081
Applying the quadratic formula :
617 ± √ 1150081
x = —————————
-548
√ 1150081 , rounded to 4 decimal digits, is 1072.4183
So now we are looking at:
x = ( 617 ± 1072.418 ) / -548
Two real solutions:
x =(617+√1150081)/-548=-3.083
or:
x =(617-√1150081)/-548= 0.831
Two solutions were found :
- x =(617-√1150081)/-548= 0.831
- x =(617+√1150081)/-548=-3.083
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