Question

solve for x: 3x²-9x-30=0​

Answer 1

Answer:

.the answer is 3 only....okk

Answer 2

Step-by-step explanation:

Solving x2-3x-10 = 0 by Completing The Square .

Add 10 to both side of the equation :

x2-3x = 10

Now the clever bit: Take the coefficient of x , which is 3 , divide by two, giving 3/2 , and finally square it giving 9/4

Add 9/4 to both sides of the equation :

On the right hand side we have :

10 + 9/4 or, (10/1)+(9/4)

The common denominator of the two fractions is 4 Adding (40/4)+(9/4) gives 49/4

So adding to both sides we finally get :

x2-3x+(9/4) = 49/4

Adding 9/4 has completed the left hand side into a perfect square :

x2-3x+(9/4) =

(x-(3/2)) • (x-(3/2)) =

(x-(3/2))2

Things which are equal to the same thing are also equal to one another. Since

x2-3x+(9/4) = 49/4 and

x2-3x+(9/4) = (x-(3/2))2

then, according to the law of transitivity,

(x-(3/2))2 = 49/4

We'll refer to this Equation as Eq. #5.2.1

The Square Root Principle says that When two things are equal, their square roots are equal.

Note that the square root of

(x-(3/2))2 is

(x-(3/2))2/2 =

(x-(3/2))1 =

x-(3/2)

Now, applying the Square Root Principle to Eq. #5.2.1 we get:

x-(3/2) = √ 49/4

Add 3/2 to both sides to obtain:

x = 3/2 + √ 49/4

Since a square root has two values, one positive and the other negative

x2 - 3x - 10 = 0

has two solutions:

x = 3/2 + √ 49/4

or

x = 3/2 - √ 49/4

Note that √ 49/4 can be written as

√ 49 / √ 4 which is 7 / 2

Solve Quadratic