Correct

竭力 vs 尽力

/ jiélì vs jìnlì /
Strokes

Formula

1
尽心竭力

Definition

竭力 is an Adverb, 尽力 is a verb-object phrase, both means [do one's utmost; do one's best].

Example

竭力 is more literary, and when applied to non-positive things (negative or passive), 竭力 is used more.
1) In example ①, the two words are interchangeable, but 竭力 is more literary.

2) In example ② what 竭力 qualifies is 表示反对, anon-positive expression.

3) In example③, the positive effort is qualified by 尽力, while the negative effort by 竭力.
1
Zhè
jiàn
gōngzuò
工作
  
,
dìng
一定
jié
竭力
  
(
jìn
尽力
  
)
wánchéng
完成
  

I will do my utmost to finish the work.

2
jié
竭力
biǎoshì
表示
fǎnduì
反对
  
,
dàn
háishi
还是
méi
néng
zhǐ
阻止
jué
决议
tōngguò
通过
  

He exerted his every effort to disapprove the proposal;however,he cannot prevent it from being adopted.

3
Duì
zhège
这个
fāngàn
方案
  
,
xiē
一些
rén
jìn
尽力
zhīchí
支持
  
,
lìng
xiē
一些
rén
què
jié
竭力
náo
阻挠
  

As for the plan,some did their utmost to be for it,while some against it.

The verb and object are used separately, so 尽力 is used.
4
jīng
已经
jìn
le
quán
全力
zuò
  

I have exerted every effort to do it.

5
suīrán
虽然
méiyǒu
没有
kǎo
hǎo
  
,
dàn
jīng
已经
jìn
le
  

Though he failed, he has made every effort to do it.

竭力 can be used in the four word set phrase 尽心竭力.
尽心竭力
6
父母
jìnxīnjié
尽心竭力
péiyǎng
培养
jiào
教育
men
他们
xiōng
兄弟
liǎ
  

Their parents did their best to bring up and educate them.

Related

竭力尽力