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Given nC10 = 22nC12 determine the value of n

1 Answer

5 votes

STEP

1

:

Equation at the end of step 1

(n • (c10)) - (2•11nc12) = 0

STEP

2

:

STEP

3

:

Pulling out like terms

3.1 Pull out like factors :

nc10 - 22nc12 = -nc10 • (22c2 - 1)

Trying to factor as a Difference of Squares:

3.2 Factoring: 22c2 - 1

Theory : A difference of two perfect squares, A2 - B2 can be factored into (A+B) • (A-B)

Proof : (A+B) • (A-B) =

A2 - AB + BA - B2 =

A2 - AB + AB - B2 =

A2 - B2

Note : AB = BA is the commutative property of multiplication.

Note : - AB + AB equals zero and is therefore eliminated from the expression.

Check : 22 is not a square !!

Ruling : Binomial can not be factored as the

difference of two perfect squares

Equation at the end of step

3

:

-nc10 • (22c2 - 1) = 0

STEP

4

:

Theory - Roots of a product

4.1 A product of several terms equals zero.

When a product of two or more terms equals zero, then at least one of the terms must be zero.

We shall now solve each term = 0 separately

In other words, we are going to solve as many equations as there are terms in the product

Any solution of term = 0 solves product = 0 as well.

Solving a Single Variable Equation:

4.2 Solve -nc10 = 0

Setting any of the variables to zero solves the equation:

n = 0

c = 0

Solving a Single Variable Equation:

4.3 Solve : 22c2-1 = 0

Add 1 to both sides of the equation :

22c2 = 1

Divide both sides of the equation by 22:

c2 = 1/22 = 0.045

When two things are equal, their square roots are equal. Taking the square root of the two sides of the equation we get:

c = ± √ 1/22

The equation has two real solutions

These solutions are c = ±√ 0.045 = ± 0.21320

Four solutions were found :

c = ±√ 0.045 = ± 0.21320

c = 0

n = 0

answered
User Sagar Jadhav
by
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