Question

if a- b =0.9 and ab = 0.36 find a+ b

Answer 1

Given a-b = o.9 and ab=0.36
Now a+b =root of (a+ b) whole sq
=Root of [(a-b)^2+ 4ab]
= Root of [(0.9)^2 + 4×0.36]
= Root of [0.81 + 1.44]
=Root of [ 2.25]
= 1.5
Therefore a+b = 1.5

Answer 2

$Given \: a - b = 0.9 \: --(1)$

$ab = 0.36 \: ---(2)$

/* We know that ,

$\boxed { \pink { ( a + b )^{2} = (a -b)^{2} + 4ab }}$

$( a + b )^{2} = (0.9)^{2} + 4 \times 0.36 \\ [ From \:(1) \:and \:(2) ]$

$= 0.81 + 1.44 \\= 2.25 \\= (1.5)^{2}$

$\implies a + b = \pm \sqrt{(1.5)^{2}}\\= \pm 1.5$

Therefore.,

$\red { a + b } \green {=\pm 1.5 }$

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