are these declensions right? thanks for checking them.

bonus rex
bonis regis
boni regi
bonem regem
bone rege

reges bones (macrons on e's)
regum bonum
regibus bonibus
reges bones (macrons)
regibus bonibus

mater meu
Matris meuis
matri meui
matrem meum
matre meue
matres meues
matrem meuem
matribus meuibus
matres meues
matribus meuibus

Where are you getting these adjectives from?

The nouns look OK:
(3rd declension)
rex
regis
regi
regem
rege

reges
regum
regibus
reges
regibus

(also 3rd declension)
mater
matris
matri
matrem
matre

matres
matrum
matribus
matres
matribus

But those adjectives!! Holy smoke!! You need to make them match the nouns (which are in 3rd declension) and yet stay in their own declensions. Bonus, a, um and meus, a, um are first and second declensions.

What are the endings for first declension? They will be needed for me- to modify mater.

What are the endings for second declension? They will be needed for bon- to modify rex.

So ... the nouns are fine. Just fix the adjectives. Repost whenever you're ready.

3rd declension noun with 2nd declension adjective

rex bonus
regis boni
regi bono
regem bonum
rege bono

reges boni (macrons on e's)
regum bonorum
regibus bonis
reges bones (macrons)
regibus bonis

3rd declension noun with 1st declension adjective
mater mea
matris meae
matri meae
matrem meam
matre mea

matres meae
matrum mearum
matribus meuis
matres meas
matribus meis

(With macrons in the correct places.)

See the explanation at the top of this webpage and the charts at the bottom:
http://www.everything2.com/title/Latin%2520noun%2520declensions

matribus meuis <~~incorrect

matribus meis <~~corrected

To check if the declensions are correct, we will first need to understand the principles of Latin declension and the specific rules for each case. Let's break down the declensions for the given nouns:

1. Bonus Rex (Good King) - masculine noun of the second declension:
- Nominative: bonus rex ("bonus" as the adjective modifying "rex")
- Genitive: boni regis ("boni" agreeing with "rex" in the genitive case)
- Dative: bono regi ("bono" agreeing with "rex" in the dative case)
- Accusative: bonem regem ("bonem" agreeing with "rex" in the accusative case)
- Ablative: bone rege ("bone" agreeing with "rex" in the ablative case)

2. Reges Bones (Good Kings) - plural form:
- Nominative: reges bones ("reges" as the plural form of "rex" and "bones" agreeing in the nominative case)
- Genitive: regum bonum ("regum" agreeing with "reges" in the genitive case and "bonum" as the adjective modifying "reges")
- Dative: regibus bonibus ("regibus" agreeing with "reges" in the dative case and "bonibus" as the adjective modifying "regibus")
- Accusative: reges bones ("reges" agreeing in the accusative case and "bones" agreeing with "reges")
- Ablative: regibus bonibus ("regibus" agreeing in the ablative case and "bonibus" agreeing with "regibus")

3. Mater Mea (My Mother) - feminine noun of the first declension:
- Nominative: mater mea ("mater" as the subject and "mea" agreeing with "mater" in the nominative case)
- Genitive: matris meae ("matris" agreeing with "mater" in the genitive case and "meae" as the adjective modifying "matris")
- Dative: matri meae ("matri" agreeing with "mater" in the dative case and "meae" as the adjective modifying "matri")
- Accusative: matrem meam ("matrem" agreeing with "mater" in the accusative case and "meam" as the adjective modifying "matrem")
- Ablative: matre mea ("matre" agreeing with "mater" in the ablative case and "mea" as the adjective modifying "matre")

4. Matres Meae (My Mothers) - plural form:
- Nominative: matres meae ("matres" as the plural form of "mater" and "meae" agreeing in the nominative case)
- Genitive: matrum mearum ("matrum" agreeing with "matres" in the genitive case and "mearum" as the adjective modifying "matrum")
- Dative: matribus meis ("matribus" agreeing with "matres" in the dative case and "meis" as the adjective modifying "matribus")
- Accusative: matres meas ("matres" agreeing in the accusative case and "meas" as the adjective modifying "matres")
- Ablative: matribus meis ("matribus" agreeing in the ablative case and "meis" as the adjective modifying "matribus")

Based on these rules, it seems that your declensions are mostly correct. However, there are a few errors to address:

1. In "bonis regis," the dative case of "regis" should be "regi" rather than "regis."

2. In "bone rege," the ablative case of "rex" should be "rege" rather than "rege."

3. In "reges bones," the nominative case of "bones" should be "boni" since it agrees with "reges" (macrons on e's is not necessary for these declensions).

4. In "matres meues" and "matribus meuibus," it should be "meae" instead of "meues" and "meis" instead of "meuibus" to indicate the possessive pronoun "my."

By making these corrections, the declensions should be:

bonus rex
boni regis
bono regi
bonem regem
bone rege

reges boni
regum bonorum
regibus bonis
reges bonos
regibus bonis

mater mea
matris meae
matri meae
matrem meam
matre mea

matres meae
matrum mearum
matribus meis
matres meas
matribus meis

Please note that these corrections are based on the standard rules of Latin declension, and there may be specific cases or variations that could apply depending on the context or grammar rules of certain Latin exercises or translations.