Question

Find this value fast please​

Answer 1

Question:-

Find the value of :

${a}^{3} + {8b}^{3} \: \: if \: \: a + 2b = 10 \: \: and \: \: ab = 15$

Solution:-

${a}^{3} + {8b}^{3} \: can \: be \: written \: as \: {a}^{3} + {(2b)}^{3}$

Given,

$a + 2b = 10$

We have

${(a + b)}^{3} = {a}^{3} + {b}^{3} + 3ab(a + b)$

So,

${(a + 2b)}^{3} = {a}^{3} + {(2b)}^{3} + 3 \times a \times 2b(a + 2b) = {10}^{3}$

Given ab = 15

Also,a+2b = 10

${a}^{3} + {(2b)}^{3} + 6 \times 15(10) = 1000$

${a}^{3} + {(2b)}^{3} + 900 = 1000$

${a}^{3} + {2b}^{3} = 1000 - 900$

${a}^{3} + {8b}^{3} = 100$

Answer 2

Answer:

bhai a ki value nikalo or b ki then solve karo baat khatam