Expand the following using the Binomial Theorem and Pascal’s triangle.

(x + 2)6
(x − 4)4
(2x + 3)5
(2x − 3y)4
In the expansion of (3a + 4b)8, which of the following are possible variable terms? Explain your reasoning.
a2b3; a5b3; ab8; b8; a4b4; a8; ab7; a6b5

Respuesta :

Answer:


Step-by-step explanation:

 Using the binomial theorem, [tex](a+b)^{n}=nc_{0}a^{n}b^{0}+nc_{1}a^{n-1}b^{1}+.......+nc_{n}a^{0}b^{n}[/tex]

[tex](x+2)^{6}=x^{6}+12x^{5}+60x^{4}+160x^{3}+240x^{2}+192x+64[/tex]

[tex](x-4)^{4}=x^{4}-16x^{3}+96x^{2}-256x+256[/tex]

[tex](2x+3)^{5}=32x^{5}+240x^{4}+720x^{3}+1080x^{2}+810x+243[/tex]

and [tex](2x-3y)^{4}=16x^{4}-96x^{3}y+216x^{2}y^{2}-216xy^{3}+81y^{4}[/tex]

Using pascal's triangle, From the given picture,

[tex](x+2)^{6}[/tex]

a=x, b=2 and n=6, using the 7th row of pascals triangle,

[tex](x+2)^{6}=1(x^{6})(6^{0})+6(x^{5})(6^{1})+15(x^{4})(6^{2})+20(x^{3})(6^{3})+15(x^{2})(6^{4})+6(x^{1})(6^{5})+1(x^{0})(6^{6})[/tex]

=[tex]x^{6}+36x^{5}+540x^{4}+432x^{3}+19440x^{2}+46656x+46656[/tex]

[tex](x-4)^{4}[/tex]

a=x, b=-4 and n=4 and using the 5th row of pascals triangle

[tex](x-4)^{4}=x^{4}-16x^{3}+96x^{2}-256+256[/tex]

[tex](2x+3)^{5}[/tex]

a=2x , b=3 and n=5, using the 6th row of pascal's triangle

[tex](2x+3)^{5}=[\tex]32x^{5}+240x^{4}+720x^{3}+1080x^{2}+810x+243[/tex]

[tex](2x-3y)^{4}[/tex]

a=2x, b=-3y, n=4, using the 5th row,

[tex](2x-3y)^{4}=[\tex]16x^{4}-96xy+216x^{2}y^{2}-216xy^{3}+81y[/tex]

Now, in the expansion of [tex](3a+4b)^{8}[/tex], The degree of the term must add up to 8. [tex]ab^{7}[/tex] is of degre 8 than the other terms, this is because [tex]ab^{7}[/tex] is same as [tex]a^{1}{\times}b^{7}[/tex], adding the components 1 and 7, we get 8.

Ver imagen boffeemadrid

Refer the below solution for the proper understanding.

Step-by-step explanation:

Solution :

Using the Binomial Theorem -

[tex](a + b)^n=nc_0a^nb^0+nc_1a^n^-^1b^1+..............+nc_na^0b^n\\[/tex]

1) [tex](x+2)^6[/tex]

[tex](x+2)^6=x^6+12x^5+60x^4+160x^3+240x^2+192x+64[/tex]

2) [tex](x-4)^4[/tex]

[tex](x-4)^4=x^4-16x^3+96x^2-256x+256[/tex]

3) [tex](2x+3)^5[/tex]

[tex](2x+3)^5=32x^5+240x^4+720x^3+1080x^2+810x+243[/tex]

4) [tex](2x-3y)^4[/tex]

[tex](2x-3y)^4=16x^4-96x^3y+216x^2y^2-216xy^3+81y^4[/tex]

Using Pascals triangle,

1) [tex](x+2)^6[/tex]

a = x , b =2 and n = 6 , using the seventh row of pascals triangle

[tex](x+2)^6= 1(x^6)(6^0)+6(x^5)(6^1)+15(x^4)(6^2)+20(x^3)(6^3)+15(x^2)(6^4)+6(x^1)(6^5)+1(x^0)(6^6)[/tex]

[tex](x+2)^6 = x^6+36x^5+540x^4+432x^3+19440x^2+46656x+46656[/tex]

2) [tex](x-4)^4[/tex]

a = x , b = -4 and n = 4, using the fifth row of pascals triangle

[tex](x-4)^4= x^4-16x^3+96x^2-256x+256[/tex]

3) [tex](2x+3)^5[/tex]

a = 2x , b = 3 and n = 5, using the sixth row of pascals triangle

[tex](2x+3)^5=32x^5+240x^4+720x^3+1080x^2+810x+243[/tex]

4) [tex](2x-3y)^4[/tex]

a = 2x , b = -3y and n = 4, using the fifth row of pascals triangle

[tex](2x-3y)^4= 16x^4-96x^3+216x^2-216x+81[/tex]

Now, in the expansion of

[tex](3a + 4b)^8[/tex]

The degree of the term must add up to 8.

[tex]ab^7[/tex] is of degre 8 than the other terms, this is because [tex]ab^7[/tex] is same as [tex]a^1b^7[/tex], adding the components 1 and 7, we get 8.

For more information, refer the link given below

https://brainly.com/question/16978014?referrer=searchResults

Ver imagen ankitprmr2