Usage: 11 forms in 22 verses
Form Translated As     In Verse(s)
ηγαθύνθη did good LXX.Ruth.3.7
good LXX.Dan.6.23
it was good LXX.Judg.18.20LXX.Neh.2.6
was good LXX.Judg.16.25
ηγάθυνασ you did good LXX.Ruth.3.10LXX.2Kgs.10.30
αγαθύνησ you should do good LXX.Ps.49.18
αγαθύναι make good LXX.1Kgs.1.47
to do good LXX.Ps.36.3
αγαθυνθήτω do good LXX.Judg.19.6LXX.Judg.19.9
αγαθυνθήσεται shall seem good LXX.Neh.2.5
will be made better LXX.Eccl.7.3
αγαθυνθή good LXX.2Sam.13.28
should seem good LXX.Ezra.7.18
αγαθυνθέντων good LXX.Judg.19.22
αγαθυνεί lord shall do good LXX.1Sam.25.31
shall do good LXX.1Sam.2.32
αγαθυνάτω do you good LXX.Eccl.11.9
αγάθυνον Do good LXX.Ps.51.18LXX.Ps.125.4

Liddell-Scott-Jones

ἀγαθύνω (agathunō) be better G:V

ἀγαθύνω-ύνω,

first and frequently in LXX:

__I honour, magnify, [LXX]: adorn, τὴν κεφαλήν[Refs]
__I.2 cheer, ἀγαθύνωυνάτω σε καρδία[LXX]:—passive, to be of good cheer, rejoice greatly, [LXX]
__II make good, [Refs 3rd c.AD+]: passive, [Refs 6th c.AD+]
__II.b Astrology texts, make beneficent, in passive, [Refs 2nd c.AD+]
__III do good to, τινά[Refs]
__IV do good, do well, [LXX]

LSJ Scripture Refs: LXX.Ps.50.18*LXX.Eccl.11.9 ☩ LXX.2Kgs.13.28 ☩ LXX.Dan.6.23*LXX.Ps.35.3*