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Mathematics

Given :

log3 m = x and log3 n = y

(i) Express 32x - 3 in terms of m.

(ii) Write down 31 - 2y + 3x in terms of m and n.

(iii) If 2 log3 A = 5x - 3y; find A in terms of m and n.

Logarithms

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Answer

Given,

1st equation :

⇒ log3 m = x

⇒ m = 3x ……(1)

2nd equation :

⇒ log3 n = y

⇒ n = 3y ……(2)

(i) Given,

32x - 3

⇒ 32x.3-3

⇒ (3x)2.3-3

Substituting value of 3x from equation (1) in above equation, we get :

⇒ m2.3-3

m233\dfrac{m^2}{3^3}

m227\dfrac{m^2}{27}.

Hence, 32x - 3 = m227\dfrac{m^2}{27}.

(ii) Simplifying the expression,

⇒ 31 - 2y + 3x

⇒ 31.3-2y.33x

⇒ 3.(3y)-2.(3x)3

Substituting value of 3x and 3y from equation (1) and (2) in above equation, we get :

⇒ 3.n-2.m3

3m3n2\dfrac{3m^3}{n^2}.

Hence, 31 - 2y + 3x = 3m3n2\dfrac{3m^3}{n^2}.

(iii) Given,

⇒ 2log3 A = 5x - 3y

⇒ log3 A2 = 5x - 3y

⇒ A2 = 35x - 3y

⇒ A2 = 35x.3-3y

⇒ A2 = (3x)5.(3y)-3

Substituting value of 3x and 3y from equation (1) and (2) in above equation, we get :

⇒ A2 = m5.n-3

⇒ A2 = m5n3\dfrac{m^5}{n^3}

⇒ A = m5n3\sqrt{\dfrac{m^5}{n^3}}.

Hence, A = m5n3\sqrt{\dfrac{m^5}{n^3}}.

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