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Expand and simplify the following: 3(z + 6) – 2(4z + 1)

Expand the brackets: (3z + 18) - (8z + 2) Simplify: 16 - 5z
RW
Answered by Ryan W. • Maths tutor
4326 Views

Make a the subject of a+3=(2a+7)/r

Times both side by r to get ar+3r=2a+7 Subtract 2a and 3r from both side to bring a to one side, ar-2a=7-3r Factorise the left handside, a(r-2)=7-3r Divide both side by r-2, a=(7-3r)/(r-2)
AH
Answered by Arafatul H. • Maths tutor
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What is the probability of picking a red ball twice from a bag of 6 blue balls and 3 red balls, without replacement.

The probability of picking a ball from a bag is the number of balls of that colour divided by the total number of balls. Therefore in the first instance, the probability of a red ball is 3/9 or 1/3rd. If tha...
TF
Answered by Toby F. • Maths tutor
41777 Views

If a bag contains 6 green balls and 3 red balls, what the probability of picking out 2 red, with and without replacement.

For the first ball the probability we pick a red ball is the same, it's the number of red balls divided by the total number of balls. Which in this case is 3/9. If we replace the balls the chance of picking ...
TF
Answered by Toby F. • Maths tutor
23409 Views

Find where the curve 2x^2 + xy + y^2 = 14 has stationary points

d/dx (xy) = x dy/dx + y d/dx (y^2) = 2y dy/dx [This is from the chain rule] So, d/dx (2x^2 + xy + y^2 = 14) => 4x + x dy/dx + y + 2y dy/dx = 0 set dy/dx = 0 as stationary point has gradient 0 Obtains 4x+y...
MH
Answered by Matthew H. • Maths tutor
9184 Views