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C2 Algebra

hi guys

this will probably be v easy but i just cant seem to figure the answer out!!!!

Question:

f(x) = 2x3 - 5x2 - 4x +3

Given that f(x) is exactly divisible by (x - 3)

Solve the eqn f(x) = 0

thnx guys v much appreciated

frm hatty341 :biggrin:

Reply 1

Libertine

[QUOTE="hatty341"]hi guys

this will probably be v easy but i just cant seem to figure the answer out!!!!

Question:

f(x) = 2x3 - 5x2 - 4x +3

2x³ - 5x² - 4x + 3 = 0
(x-3)(2x²+x-1) = 0
(x-3)(2x-1)(x+1) = 0
x = 3, 1/2, -1

Reply 2

hatty341

Libertine

2x³ - 5x² - 4x + 3 = 0
(x-3)(2x²+x-1) = 0
(x-3)(2x-1)(x+1) = 0
x = 3, 1/2, -1

omg! it was that easy, why couldnt i get it!! anyhoo... thnx so much Libertine!!!!!

2 more questions i need help with:

Questions:

Reply 3

dvs

1. Find the gradient of PQ then the gradient of QR, and show that when you multiply them together you get -1. This will mean they're perpendicular.

2. Differentiate and get the value of dy/dx at (4, 7). This will be the gradient of the tangent (i.e. m). And since you know that the tangent passes through the point (4, 7), then you can find c.