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X^2+4x-21=0 Solve for x

Quadractics factorise into double brackets like (x-a)(x-b). We ave to find the facors of -21 which add to make +4. 7 and -3 suffice. (x-3)(x+7) Then x will be equal to 3 and -7 for the equation.
JC
Answered by James C. • Maths tutor
5503 Views

Solve this pair of simultaneous equations: 3x + y= 7 and 3x - y = 5

Step 1: Start off by labeling the 2 equations. 3 x + y = 7 will be equation 1. 3 x - y = 5 will be equation 2. Step 2: rearrange equation 1 to make y the subject. 3 x + y = 7 ---> y = 7 - 3 x (here 3 x is...
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Answered by Anna G. • Maths tutor
15918 Views

Solve the simultaneous equations 2a + b =4 and 5a – 3b = -1

When you solve normal equations like 4x-2=7, there is one equation and one unknown value. This case is no different: in order to solve these equations, you need to create one equation with one unknown. We st...
MM
Answered by Molly M. • Maths tutor
15234 Views

Is there an easy way of telling whether a noun is masculine or feminine?

The official answer for this question is that you have to learn the gender of each new noun individually. However, quite often it is possible to guess the gender of nouns from their endings. For example, all...
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Answered by Molly M. • French tutor
3564 Views

What is the difference between ser and estar?

the two verbs ser and estar, in Castilian Spanish both mean "to be" in English. The confusion for non native speakers comes when trying to identify within which contexts you are supposed to use whi...
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Answered by Rhys C. • Spanish tutor
3004 Views