Question

If a + 2b = 3 and ab = -5, then find the value of
(1)a^+4b^
(ii) a3 + 8b3​

Answer 1

$\mathfrak{\underline{\underline{\green{Answer:-}}}}$

a²+4b² = 29

a³+8b³ = 117

$\mathfrak{\underline{\underline{\green{Explanation:-}}}}$

Given:

a+2b = 3

ab = -5

___________________

(1) a²+4b²

Given that,

a+2b = 3

by squaring on both sides

(a+2b)² = 3²

a²+4b²+4ab = 9

a²+4b²+4(-5) = 9

a²+4b² -20 = 9

a²+4b² = 9+20

$\boxed{{a}^{2}+4{b}^{2} = 29}$

_____________________

(2) a³+8b³

we have,

a+2b = 3

by cubing on both sides

(a+2b)³ = 3³

a³+8b³+3(a)(2b)(a+2b) = 27

a³+8b³+6ab(3) = 27

a³+8b³+6(-5)(3) = 27

a³+8b³-90 = 27

a³+8b³ = 27+90

$\boxed{{a}^{3}+8{b}^{3}= 117}$

Answer 2

Answer:

■In attatchment ..........