Let p(x) = 30 x^3 -7 x^2 - 7 x + 2. Prove that (2x + 1) is a factor of p(x) and factorise p(x) completely.

Using the Factor Theorem, we know that (2x + 1) = 2(x + 1/2) = 2(x - (-1/2) ) is a factor of p(x) if and only if p(-1/2) = 0, which is true. Now that we know a factor of p(x), we use the polynomial division method to find p(x) = (2x + 1)(15 x^2 - 11x + 2) and factorise the quadratic with some simple algebra 15 x^2 - 11x + 2 = 15 x^2 - 5x - 6x + 2 = 5x(3x - 1) - 2(3x - 1) = (3x - 1)(5x - 2), which gives us the final answer: p(x) = (2x + 1)(3x - 1)(5x - 2).

Answered by Maths tutor

4079 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Express 5cosx - 3sinx in the form Rcos(x+a).


Integrate sinx*ln(cosx) with respect to x.


Given y=2x(x^2-1)^5, show that dy/dx = g(x)(x^2-1)^4 where g(x) is a function to be determined.


x = 2t + 5, y = 3 + 4/t. a) Find dy/dx at (9.5) and b) find y in terms of x.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences