Maths halp! (1 Viewer)

[Frostbitten]

Factorise a^2 - 4a + 4 - 9b^2

Thankyou

 

[chris_power_96]

=(a-2)^2-9b^2
=(a-2+3b)(a-2-3b)

 

[Trebla]

Factorise a^2 - 4a + 4 - 9b^2

Thankyou

The first three terms factorise into a perfect square so you get
(a - 2)² - 9b²
which is a difference of two squares so can be factorised into
(a - 2 - 3b)(a - 2 + 3b)

 

[Frostbitten]

Ahhh ok, thanks guys

Also, how come sometimes linear equations are in the form ax + by + c = 0 and not ax + by = c?

 

[Frostbitten]

New question yay.

The geometric series a+ar+ar^2 has a second term of 1/4 and has a limiting sum of 1.
I) show that a=1-r
II) solve a pair of simultaneous equations to find r

 

[Frostbitten]

barhmp

 

[Frostbitten]

Somene save me from this demon called maths arrggg

 

[Carrotsticks]

New question yay.

The geometric series a+ar+ar^2 has a second term of 1/4 and has a limiting sum of 1.
I) show that a=1-r
II) solve a pair of simultaneous equations to find r

I) Since the limiting sum is 1, then a/(1-r) = 1, and therefore a = 1-r

II) Since the second term is 1/4, ar = 1/4.

So we have a = 1-r and ar = 1/4. Solving simultaneously, we have (1-r)*r = 1/4 and solve as per usual.

 

[Frostbitten]

I) Since the limiting sum is 1, then a/(1-r) = 1, and therefore a = 1-r

II) Since the second term is 1/4, ar = 1/4.

So we have a = 1-r and ar = 1/4. Solving simultaneously, we have (1-r)*r = 1/4 and solve as per usual.

Oh you are an angel from heaven

 

[Carrotsticks]

Oh you are an angel from heaven

If only I was also duh sexy