An algebra problem by Saksham Mittal

Algebra Level 3

a a + b b = 183 \large a\sqrt{a}+b\sqrt{b}=183 a b + b a = 182 \large a\sqrt{b}+b\sqrt{a}=182

Find the value of 9 5 ( a + b ) \dfrac{9}{5}({a+b})


The answer is 73.

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2 solutions

Sumukh Bansal
Nov 13, 2017

@Saksham Mittal Make the problem better by changing it into latex.There are many guides which may help.And as for your question"Is it difficult???" Nope it's not

@Sumukh Bansal I dont know how to use latex....teach it to me in school....

Saksham Mittal - 3 years, 6 months ago

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You could toggle the latex and then copy and paste it in your problem

Sumukh Bansal - 3 years, 6 months ago

I will give you the code you upgrade them.

Sumukh Bansal - 3 years, 6 months ago

a a + b b = 183 \large a\sqrt{a}+b\sqrt{b}=183 a b + b a = 182 \large a\sqrt{b}+b\sqrt{a}=182 Find the value of 9 5 ( a + b ) \dfrac{9}{5}({a+b})

Sumukh Bansal - 3 years, 6 months ago
Vilakshan Gupta
Nov 13, 2017

Let a = c \sqrt{a}=c and b = d \sqrt{b}=d so that a + b = c 2 + d 2 a+b=c^2+d^2 .

Now c 3 + d 3 = 183 c^3+d^3=183 and c 2 d + c d 2 = c d ( c + d ) = 182 c^2d+cd^2=cd(c+d)=182 .

Note that c 3 + d 3 = ( c + d ) 3 3 c d ( c + d ) = 183 c^3+d^3=(c+d)^3-3cd(c+d)=183 \implies ( c + d ) 3 3 × 182 = 183 (c+d)^3-3 \times 182 = 183 .

( c + d ) 3 = 729 c + d = 9 \implies (c+d)^3=729 \implies c+d=9 and therefore c d = 182 9 cd=\frac{182}{9} .

Now

a + b = c 2 + d 2 = ( c + d ) 2 2 c d = 81 364 9 = 365 9 \begin{aligned} a+b & = c^2+d^2 = (c+d)^2-2cd \\ & = 81 - \frac{364}{9} \\ & = \frac{365}{9} \end{aligned}

Therefore 9 5 ( a + b ) = 9 5 × 365 9 = 73 \frac95(a+b)=\frac95 \times \frac{365}9=\boxed{73}


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