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Aditi, Becky and Cali collect coins. Aditi has 6 more coins than Becky. Cali has 1 less coin than Aditi. Altogether they have 71 coins. How many coins do they each have? Show all your working.

Form 3 equations. Equation 1: A= 6+ B.Equation 2 : C= A-1. Equation 3: A+ B+ C= 71.Substitute equation 1 and 2 into 3 to get: 6+ B + B + A - 1= 71 -> 2B + A= 66 which is equation 4. Then, substitute equat...
KS
Answered by Kelvin S. • Maths tutor
7767 Views

Differentiate the equation y = (2x+5)^2 using the chain rule to determine the x coordinate of a stationary point on the curve.

Use the chain rule as this is a composite function. Let u=2x+5.So the original equation becomes y=(u)^2.Using the chain rule: dy/dx = dy/du * du/dxdy/du = 2udu/dx = 2So dy/dx= 4uSince u=2x+5, dy/dx = 4(2x+5)...
DP
Answered by Daniel P. • Maths tutor
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How do you solve simultaneous equations?

There are two main methods:Substitution and elimination which can be demonstrated on the white board.
AC
Answered by Adham C. • Maths tutor
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Show that 2sin(x) =(4cos(x)-1)/tan(x) can be written as: 6cos^2(x)-cos(x)-2=0

Rearranging gives:4cos(x)-1 = 2sin(x) tan(x) Substituting in tan(x)=sin(x)/cos(x) gives:4cos(x)-1 = 2sin(x) (sin(x)/cos(x))2sin 2 (x)=4cos 2 (x)-4cos(x)Substituting in 2sin 2 (x) = 2-2cos 2 (x) (from the tri...
OT
Answered by Olivia T. • Maths tutor
17764 Views

The General Form of the equation of a circle is x^2 + y^2 + 2gx +2fy + c = 0. Find the centre of the circle and the radius of the circle in terms of g f and c.

Given a circle in the general form you can complete the square to change it into the standard form.x 2 + 2gx + y 2 +2fy +c = 0 (1). General form of an equation which has the completing the square method appl...
RS
Answered by Rushabh S. • Maths tutor
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