## Step 1 :

Equation in ~ the end of action 1 : ((0 - 5x2) - 28x) - 15 = 0

## Step 3 :

Pulling out prefer terms :3.1 pull out like factors:-5x2 - 28x - 15=-1•(5x2 + 28x + 15)

Trying to aspect by dividing the center term

3.2Factoring 5x2 + 28x + 15 The an initial term is, 5x2 the coefficient is 5.The center term is, +28x that coefficient is 28.The critical term, "the constant", is +15Step-1 : multiply the coefficient of the first term through the continuous 5•15=75Step-2 : discover two determinants of 75 whose sum amounts to the coefficient the the middle term, i beg your pardon is 28.

 -75 + -1 = -76 -25 + -3 = -28 -15 + -5 = -20 -5 + -15 = -20 -3 + -25 = -28 -1 + -75 = -76 1 + 75 = 76 3 + 25 = 28 That"s it

Step-3 : Rewrite the polynomial dividing the center term utilizing the two determinants found in step2above, 3 and also 255x2 + 3x+25x + 15Step-4 : add up the first 2 terms, pulling out like factors:x•(5x+3) include up the last 2 terms, pulling out typical factors:5•(5x+3) Step-5:Add increase the 4 terms of step4:(x+5)•(5x+3)Which is the preferred factorization

Equation in ~ the finish of action 3 :

(-5x - 3) • (x + 5) = 0

## Step 4 :

Theory - roots of a product :4.1 A product of number of terms equals zero.When a product of 2 or an ext terms amounts to zero, climate at the very least one that the terms have to be zero.We shall currently solve each term = 0 separatelyIn other words, we space going to solve as many equations together there space terms in the productAny equipment of ax = 0 solves product = 0 together well.

Solving a single Variable Equation:4.2Solve:-5x-3 = 0Add 3 to both sides of the equation:-5x = 3 multiply both sides of the equation by (-1) : 5x = -3 divide both sides of the equation through 5:x = -3/5 = -0.600

Solving a solitary Variable Equation:4.3Solve:x+5 = 0Subtract 5 native both political parties of the equation:x = -5

### Supplement : solving Quadratic Equation Directly

Solving 5x2+28x+15 = 0 straight Earlier we factored this polynomial by dividing the middle term. Let us currently solve the equation by completing The Square and also by using the Quadratic Formula

Parabola, recognize the Vertex:5.1Find the peak ofy = 5x2+28x+15Parabolas have a highest or a lowest suggest called the Vertex.Our parabola opens up up and accordingly has a lowest point (AKA pure minimum).We understand this even prior to plotting "y" since the coefficient the the very first term,5, is confident (greater than zero).Each parabola has a vertical line of symmetry the passes v its vertex. Thus symmetry, the heat of the opposite would, for example, pass with the midpoint the the 2 x-intercepts (roots or solutions) that the parabola. The is, if the parabola has indeed two real solutions.Parabolas have the right to model numerous real life situations, such together the height over ground, of things thrown upward, ~ some period of time. The crest of the parabola can carry out us with information, such together the maximum height that object, thrown upwards, have the right to reach. Hence we want to have the ability to find the works with of the vertex.For any type of parabola,Ax2+Bx+C,the x-coordinate that the crest is given by -B/(2A). In our instance the x coordinate is -2.8000Plugging into the parabola formula -2.8000 because that x we have the right to calculate the y-coordinate:y = 5.0 * -2.80 * -2.80 + 28.0 * -2.80 + 15.0 or y = -24.200

Parabola, Graphing Vertex and X-Intercepts :

Root plot because that : y = 5x2+28x+15 Axis of the opposite (dashed) x=-2.80 Vertex at x,y = -2.80,-24.20 x-Intercepts (Roots) : root 1 in ~ x,y = -5.00, 0.00 root 2 in ~ x,y = -0.60, 0.00

Solve Quadratic Equation by perfect The Square

5.2Solving5x2+28x+15 = 0 by completing The Square.Divide both political parties of the equation through 5 to have 1 as the coefficient that the first term :x2+(28/5)x+3 = 0Subtract 3 indigenous both side of the equation :x2+(28/5)x = -3Now the clever bit: take the coefficient of x, i beg your pardon is 28/5, divide by two, offering 14/5, and finally square it offering 196/25Add 196/25 to both sides of the equation :On the best hand side us have:-3+196/25or, (-3/1)+(196/25)The typical denominator the the 2 fractions is 25Adding (-75/25)+(196/25) provides 121/25So including to both political parties we finally get:x2+(28/5)x+(196/25) = 121/25Adding 196/25 has completed the left hand side right into a perfect square :x2+(28/5)x+(196/25)=(x+(14/5))•(x+(14/5))=(x+(14/5))2 points which space equal come the same thing are also equal to one another. Sincex2+(28/5)x+(196/25) = 121/25 andx2+(28/5)x+(196/25) = (x+(14/5))2 then, follow to the law of transitivity,(x+(14/5))2 = 121/25We"ll describe this Equation together Eq.

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#5.2.1 The Square source Principle states that when two things space equal, their square roots are equal.Note the the square root of(x+(14/5))2 is(x+(14/5))2/2=(x+(14/5))1=x+(14/5)Now, using the Square source Principle to Eq.#5.2.1 we get:x+(14/5)= √ 121/25 Subtract 14/5 indigenous both sides to obtain:x = -14/5 + √ 121/25 because a square root has two values, one positive and the other negativex2 + (28/5)x + 3 = 0has two solutions:x = -14/5 + √ 121/25 orx = -14/5 - √ 121/25 note that √ 121/25 have the right to be created as√121 / √25which is 11 / 5