Cov lej tsis paub: kev daws teeb meem yam tsis muaj teeb meem. Peb niaj hnub ntsib nrog cov kev suav suav nrog cov zauv ntawm ntuj, uas yog ntxiv, rho tawm, sib tshooj thiab sib faib. Kev kawm ua haujlwm yog qhov tseem ceeb heev, tab sis yog tias koj muaj teeb meem nrhiav qhov kev daws teeb meem thiab tsis paub siv kev ua haujlwm, nws yuav tsis muaj txiaj ntsig. Ntxiv rau kev suav, yog li ntawd, nws yog ib qho tseem ceeb kom paub txog yuav ua li cas, kev xyuam xim rau cov lus qhia hauv cov teeb meem yuav kom daws tau.

Mariana yuav 3 cwjmem thiab cov xaum qhuav siv tshuab, thiab siv 60 reais. Yog hais tias tus xaum xaum thev naus laus zis raug nqi 24 reais, ib tus xaum ntawv raug nqi li cas?

Yuav kom daws tau qhov teeb meem no, peb yuav tsum rho tawm tag nrho cov nyiaj (60) los ntawm tus nqi ntawm tus mem hluav tshuab (24).

60-24 = 36.

Nrog qhov ntawd, peb muaj 36 reais yog tus nqi them hauv cwjmem. Tab sis yuav ua li cas koj paub txhua tus nqi ib zaug? Cias faib 36 los ntawm 3 cwjmem uas yuav:

36 / 3 = 12

Ntawd yog, txhua tus cwj mem raug nqi 12 reais, thaum tus xaum xaum tus nqi them nqi 24 reais.

Teeb meem nrog tus lej tsis paub

Kev ua lej yuav siv tau nyob rau txhua hnub los daws cov teeb meem ntau yam uas nyob ib puag ncig cov naj npawb tsis paub, feem ntau sawv cev los ntawm cov tsiaj ntawv. Piv txwv li:

Dab tsi yog tus lej uas tau ntxiv rau nws ob zaug ntxiv 12 ua vim li cas?

Yuav kom daws tau qhov teeb meem no, peb yuav tsum xaiv cov naj npawb thiab ua cov kev suav.

Daws teeb meem

X - naj npawb tsis paub

2x - ob npaug ntawm cov naj npawb tsis paub

x + 2x - naj npawb tsis paub suav nrog ob npaug

x + 2x = 12 - kab zauv uas muaj teeb meem

Yuav kom daws tau, tsuas yog sau tib co ntawv nkaus xwb. Xyuas nws:

x + 2x = 12

3x = 12

x = 12/3 hli

x = 4 os

Puas tau nkag siab Cia peb pom cov piv txwv ntxiv:

tsis paub (2)

Teeb meem

Dab tsi yog tus lej uas, ntxiv rau nws qhov feem plaub, cov qhabnias hauv tus lej 25?

X - naj npawb tsis paub

4x - Plaub npaug

X + 4x - naj npawb ntxiv rau plaub ceg

x + 4x = 25 - kab zauv

Daws teeb meem

x + 4x = 25

5 x = 25 po

x = 5/25 hli

x = 5 os