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erastovalidia [21]
3 years ago
10

Solve this equation for x: 2x^2 + 12x - 7 = 0

Mathematics
1 answer:
zhannawk [14.2K]3 years ago
6 0

Answer:

x=0.5355 or x=-6.5355

First step is to: Isolate the constant term by adding 7 to both sides

Step-by-step explanation:

We want to solve this equation: 2x^2 + 12x - 7 = 0

On observation, the trinomial is not factorizable so we use the Completing the square method.

Step 1: Isolate the constant term by adding 7 to both sides

2x^2 + 12x - 7+7 = 0+7\\2x^2 + 12x=7

Step 2: Divide the equation all through by the coefficient of x^2 which is 2.

x^2 + 6x=\frac{7}{2}

Step 3: Divide the coefficient of x by 2, square it and add it to both sides.

Coefficient of x=6

Divided by 2=3

Square of 3=3^2

Therefore, we have:

x^2 + 6x+3^2=\frac{7}{2}+3^2

Step 4: Write the Left Hand side in the form (x+k)^2

(x+3)^2=\frac{7}{2}+3^2\\(x+3)^2=12.5\\

Step 5: Take the square root of both sides and solve for x

x+3=\pm\sqrt{12.5}\\x=-3\pm \sqrt{12.5}\\x=-3+ \sqrt{12.5}, $ or $x= -3- \sqrt{12.5}\\$x=0.5355 or x=-6.5355

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Reduced fraction:

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Oliga [24]

QUESTION 9

The given right angle triangle has its two legs equal to x\:cm and the hypotenuse is 2\:units.


Using the Pythagoras theorem, we have

x^2+x^2=2^2


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QUESTION 10


The given right angle triangle has its two legs equal to x\:units and the hypotenuse is 7\:units.


Using the Pythagoras theorem, we have

x^2+x^2=7^2


This implies that;

2x^2=7^2


2x^2=49


x^2=24.5


x=\sqrt{24.5}



x=4.95\:units


QUESTION 11

Sam divided the square backyard into two sections along the 40ft diagonal.

Let one of the sides of the garden be x\:units, then the other side of the garden is also  x\:units since it was a square backyard.


The diagonal is the hypotenuse which is 40ft and the two legs are  x\:units each.


Applying the Pythagoras Theorem, we have;

x^2+x^2=40^2


2x^2=1600


x^2=800


\Rightarrow x=\sqrt{800}


\Rightarrow x=28.28


The length of one side of the garden is approximately 28cm.


QUESTION 12

The hypotenuse of Nicole's right triangular support is 92cm long.


It was given that the two lengths of the triangular support are of equal length.


Let the two lengths of the triangular support be l\:cm each.


We then apply the Pythagoras theorem to obtain;

l^2+l^2=92^2


\Rightarrow 2l^2=8464


\Rightarrow l^2=4232


\Rightarrow l=\sqrt{4232}


\Rightarrow l=65.05cm


Therefore Nicole needs l+l=65.05cm+65.05cm\approx130cm of wood to complete the support.

The correct answer is A.


QUESTION 13

A 45-45-90 triangle is an isosceles right triangle.


Let the length of the two legs be m\:inches each.

It was given that the hypotenuse of this triangle is 12\:inches.


Applying the Pythagoras Theorem, we have;

m^2+m^2=12^2


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The length of one leg of the hypotenuse is approximately 8.5 inches to 1 decimal place.


QUESTIONS 14.

It was given that the distance from home plate to first base is 90 feet.


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We want to calculate the distance from home plate to 2nd base,which is the diagonal of the square baseball field.

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Therefore the distance from home plate to second base is 127 ft to the nearest foot.


QUESTION 15.

The distance from third base to  first base is also 127 ft to the nearest foot.


The reason is that the  diagonals of a square are equal in length.


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