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3 years ago

5. If x + x-1 = a, express x2 + 2 + x-2 in terms of a.

Mathematics

1 answer:

yawa3891 [41]3 years ago

3 0

I suppose the question is, if $x+x^{-1}=a$ , what is $x^2+2+x^{-2}$ ?

Recall that $(a+b)^2=a^2+2ab+b^2$ . It follows that for $x\neq0$ ,

$x^2+2+x^{-2}=x^2+2xx^{-1}+(x^{-1})^2=(x+x^{-1})^2=\boxed{a^2}$

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Factorise the following.

spin [16.1K]

Answer:

x²(9x– 11)(9x + 11)

Step-by-step explanation:

81x⁴ – 121x²

The expression can be factorised as follow:

81x⁴ – 121x²

x² is common to both term. Thus:

81x⁴ – 121x² = x²(81x² – 121)

Recall:

81 = 9²

121 = 11²

Therefore,

x²(81x² – 121) = x²(9²x² – 11²)

= x²[(9x)² – 11²]

Difference of two squares

x²(9x– 11)(9x + 11)

Therefore,

81x⁴ – 121x² = x²(9x– 11)(9x + 11)

3 0

3 years ago

Any 10th grader solve it for 50 points

kkurt [141]

Answer:

$\frac{a}{p}\times (q-r)+\frac{b}{q}\times (r-p)+\frac{c}{r}\times (p-q)\neq 0$ is proved for the sum of pth, qth and rth terms of an arithmetic progression are a, b,and c respectively.

Step-by-step explanation:

Given that the sum of pth, qth and rth terms of an arithmetic progression are a, b and c respectively.

First term of given arithmetic progression is A

and common difference is D

ie., $a_{1}=A$ and common difference=D

The nth term can be written as

$a_{n}=A+(n-1)D$

pth term of given arithmetic progression is a

$a_{p}=A+(p-1)D=a$

qth term of given arithmetic progression is b

$a_{q}=A+(q-1)D=b$ and

rth term of given arithmetic progression is c

$a_{r}=A+(r-1)D=c$

We have to prove that

$\frac{a}{p}\times (q-r)+\frac{b}{q}\times (r-p)+\frac{c}{r}\times (p-q)=0$

Now to prove LHS=RHS

Now take LHS

$\frac{a}{p}\times (q-r)+\frac{b}{q}\times (r-p)+\frac{c}{r}\times (p-q)$

$=\frac{A+(p-1)D}{p}\times (q-r)+\frac{A+(q-1)D}{q}\times (r-p)+\frac{A+(r-1)D}{r}\times (p-q)$

$=\frac{A+pD-D}{p}\times (q-r)+\frac{A+qD-D}{q}\times (r-p)+\frac{A+rD-D}{r}\times (p-q)$

$=\frac{Aq+pqD-Dq-Ar-prD+rD}{p}+\frac{Ar+rqD-Dr-Ap-pqD+pD}{q}+\frac{Ap+prD-Dp-Aq-qrD+qD}{r}$

$=\frac{[Aq+pqD-Dq-Ar-prD+rD]\times qr+[Ar+rqD-Dr-Ap-pqD+pD]\times pr+[Ap+prD-Dp-Aq-qrD+qD]\times pq}{pqr}$

$=\frac{Arq^{2}+pq^{2} rD-Dq^{2} r-Aqr^{2}-pqr^{2} D+qr^{2} D+Apr^{2}+pr^{2} qD-pDr^{2} -Ap^{2}r-p^{2} rqD+p^{2} rD+Ap^{2} q+p^{2} qrD-Dp^{2} q-Aq^{2} p-q^{2} prD+q^{2}pD}{pqr}$

$=\frac{Arq^{2}-Dq^{2}r-Aqr^{2}+qr^{2}D+Apr^{2}-pDr^{2}-Ap^{2}r+p^{2}rD+Ap^{2}q-Dp^{2}q-Aq^{2}p+q^{2}pD}{pqr}$

$=\frac{Arq^{2}-Dq^{2}r-Aqr^{2}+qr^{2}D+Apr^{2} -pDr^{2}-Ap^{2}r+p^{2}rD+Ap^{2}q-Dp^{2}q-Aq^{2}p+q^{2}pD}{pqr}$

$\neq 0$

ie., $RHS\neq 0$

Therefore $LHS\neq RHS$

ie., $\frac{a}{p}\times (q-r)+\frac{b}{q}\times (r-p)+\frac{c}{r}\times (p-q)\neq 0$

Hence proved

5 0

3 years ago

Nicolas bought a map of the city uses a scale of 1 inch to 8 miles Nickolas his house and school are 1 1 over 2 inches apart on

Nikolay [14]

Answer:

What is the question

Step-by-step explanation:

4 0

2 years ago

Find the measure of the acute angles pls help

tangare [24]

Answer:

60 degrees

and

52 degrees

6 0

3 years ago

Sometimes the unit price on two sizes of the same product will be the same. When this is the case, how will different kinds of d

mamaluj [8]

The different type of discount effected on the prices of two similar products having the same unit price may either increase or decrease the total unit price on the discounted sale price of the items.

Taking an hypothetical scenario :

50 ml of Product A = $100

60 ml of product A = $100

Discount on sale of 60ml size on purchase of two or more units : 10% off

Discounted price of 60 ml size :

Initial product cost on purchase of 3 units = ($100 × 3) = $300

Discounted price = (100 - 10)% × $300 = $270

Discount on sale for 50ml size on purchase of two or more units : $20 off

Discounted price of 50ml size :

This means $20 is deducted from any purchase of two or more units ;

Hence, purchasing 2 units of the 50 ml product will cost ; (

($100 × 2) - $20

$200 - $20 = $180

Therefore, the discount effected on the cost of product which has the same unit price may either decrease or increase the total cost of one product relative to the other.

Learn more :brainly.com/question/20418815

7 0

2 years ago