Yuav daws cov teeb meem feem ntau hauv kev ua lej hauv tsev kawm theem siab, kev paub txog kev faib ua feem yog xav tau. Qhov kev paub yooj yim no yuav pab tsis tau tsuas yog ua cov kev ua haujlwm nyuaj los ntawm phau ntawv kawm, tab sis kuj tseem nkag siab txog qhov tseem ceeb ntawm kev tshawb fawb lej. Yuav ua li cas ua kom muaj kev faib ua feem? Cia peb saib tam sim no.
Qhov piv txwv yooj yim tshaj plaws yog qhov teeb meem uas peb tsis paub thiab qhov thib plaub yuav tsum pom. Cov proportions yog, ntawm chav kawm, sib txawv, tab sis feem ntau koj yuav tsum nrhiav tau ib co zauv los ntawm feem pua. Piv txwv li, tus tub muaj kaum lub txiv apples tag nrho. Nws muab ntu plaub rau nws niam. Tus tub tshuav pes tsawg txiv apples? Qhov no yog qhov piv txwv yooj yim tshaj plaws uas yuav tso cai rau koj los ua ib feem. Qhov tseem ceeb yog ua nws. Muaj kaum lub txiv apples. Cia nws yog 100%. Qhov no peb cim tag nrho nws cov txiv apples. Nws muab ib feem plaub. 1/4=25/100. Yog li, nws tau tso tseg: 100% (nws yog Ameslikas) - 25% (nws muab)=75%. Daim duab no qhia txog qhov feem pua ntawm cov txiv hmab txiv ntoo tshuav ntawm cov txiv hmab txiv ntoo uas muaj ua ntej. Tam sim no peb muaj peb tus lej uas peb tuaj yeem daws qhov kev faib ua feem. 10 txiv apples - 100%, x txiv apples - 75%, qhov twg x yog qhov xav tau ntawm cov txiv hmab txiv ntoo. Yuav ua li cas ua kom muaj kev faib ua feem?Nws yog ib qho tsim nyog kom nkag siab tias nws yog dab tsi. Mathematical zoo li no. Daim paib sib npaug yog rau koj nkag siab.
10 apples=100%;
x apples=75%.
Nws hloov tawm tias 10 / x=100% / 75. Qhov no yog cov cuab yeej tseem ceeb ntawm proportions. Tom qab tag nrho, ntau x, ntau feem pua yog tus lej no los ntawm tus thawj. Peb daws qhov kev faib ua feem no thiab tau txais x=7.5 txiv apples. Vim li cas tus tub txiav txim siab muab tus lej tsis yog tus lej, peb tsis paub. Tam sim no koj paub yuav ua li cas ua kom muaj feem. Qhov tseem ceeb tshaj plaws yog nrhiav ob qhov sib piv, ib qho uas muaj qhov xav tau tsis paub.
Kev daws ib feem feem ntau nqes mus rau qhov yooj yim sib npaug thiab tom qab ntawd faib. Cov menyuam yaus tsis raug qhia hauv tsev kawm vim li cas qhov no yog li ntawd. Thaum nws yog ib qho tseem ceeb kom nkag siab tias kev sib raug zoo ntawm kev sib raug zoo yog lej classics, qhov tseem ceeb ntawm kev tshawb fawb. Yuav kom daws tau qhov proportions, koj yuav tsum muaj peev xwm lis cov feem. Piv txwv li, feem ntau nws yog ib qho tsim nyog los hloov cov feem pua rau cov feem zoo tib yam. Ntawd yog, cov ntaub ntawv ntawm 95% yuav tsis ua haujlwm. Thiab yog tias koj tam sim sau 95/100, ces koj tuaj yeem ua kom txo qis yam tsis tau pib suav lub ntsiab. Nws tsim nyog hais tam sim ntawd yog tias koj qhov kev faib ua feem tau tawm nrog ob yam tsis paub, ces nws tsis tuaj yeem daws tau. Tsis muaj tus xibfwb tuaj yeem pab koj ntawm no. Thiab koj txoj haujlwm, feem ntau yuav, muaj cov txheej txheem nyuaj rau kev ua kom raug.
Cia peb xav txog lwm qhov piv txwv uas tsis muaj feem pua. Tus tsav tsheb yuav 5 litre roj av rau 150 rubles. Nws xav txog seb nws yuav them li cas rau 30 litres roj. Yuav kom daws tau qhov teeb meem no, peb qhia los ntawm x tus nqi ntawm cov nyiaj. Ua taudaws qhov teeb meem no koj tus kheej thiab tom qab ntawd xyuas cov lus teb. Yog tias koj tseem tsis tau xav txog yuav ua li cas ua kom muaj kev faib ua feem, ces saib. 5 litres roj av yog 150 rubles. Raws li nyob rau hauv thawj piv txwv, cia peb sau 5l - 150r. Tam sim no cia peb nrhiav tus lej thib peb. Tau kawg, nws yog 30 litres. Pom zoo tias ib khub ntawm 30 l - x rubles yog qhov tsim nyog hauv qhov xwm txheej no. Wb hloov mus rau lus lej.
5 litres - 150 rubles;
30 litres - x rub;
5/30=150 / x.
daws qhov kev faib ua feem:
5x=30150;
x=900 rubles.
Yog li peb txiav txim siab. Hauv koj txoj haujlwm, tsis txhob hnov qab xyuas qhov txaus ntawm cov lus teb. Nws tshwm sim tias nrog qhov kev txiav txim siab tsis ncaj ncees lawm, tsheb mus txog qhov tsis muaj tseeb ntawm 5000 km ib teev thiab lwm yam. Tam sim no koj paub yuav ua li cas ua kom muaj feem. Tsis tas li koj tuaj yeem daws nws. Raws li koj tau pom, qhov no tsis nyuaj.
