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(x+3)(x-7)

= (xx) + (x-7) + (x3) + (3-7)

= x^2 - 7x + 3x - 21

= x^2 - 4x - 21

Key here is to ensure you multiply each term in one bracket by both in the other...

The stationary points on a curve of the form y=f(x) are where dy/dx = 0. To find dy/dx, differentiate using the product rule: dy/dx = 7e^x(d/dx(cosx)) + cosx(d/dx(7e^x)) = -sinx(7e^x) + cosx(7e^x). Now se...

[use of board] So, Pythagoras' theorem states that a^2+b^2=c^2. Therefore, we need to mark the triangle with a, b &c. a and b do not matter, c must be the longest edge, that creates the diagonal. Put ...

Draw the triangle. BC is opposite to the angle given and we need to find the hypotenuse. Using SOHCAHTOA, we must use sine. Rearrange to find hypotenuse and then put the numbers in. Length AC = 12cm

I like to separate problems into small steps that are easy to follow. In this example these would be: STEP 1: make y the subject (meaning only y on the Left hand side - LHS); 3y = -5x - 3. STEP 2: divide ...