Answers>Further Mathematics>GCSE>Article

(x+4)((x^2) - kx - 5) is expanded and simplified. The coefficient of the x^2 term twice the coefficient of the x term. Work out the value of k.

(x + 4) (x² - kx - 5) = x³- kx² - 5x + 4x² - 4kx - 20 = x³ + (4-k)x² + (-5-4k)x - 20.The coefficients are: (4-k) of x² and (-5-4k) of x. Now we can write the equation:(4-k) = 2(-5 - 4k) /expand4 - k = -10 - 8k /+8k4 + 7k = -10 /-47k = -14 /divide by 7k = -2

Answered by Márk F. • Further Mathematics tutor

10654 Views

(x+4)((x^2) - kx - 5) is expanded and simplified. The coefficient of the x^2 term twice the coefficient of the x term. Work out the value of k.

Related Further Mathematics GCSE answers

express z(2+i)=(1+2i)^2 in the form z=x+iy

x^3 + 2x^2 - 9x - 18 = (x^2 - a^2)(x + b) where a,b are integers. Work out the three linear factors of x^3 + 2x^2 - 9x - 18. (Note: x^3 indicates x cubed and x^2 indicates x squared).

How do I find the limit as x-->infinity of (4x^2+5)/(x^2-6)?

A curve has equation y = ax^2 + 3x, when x= -1, the gradient of the curve is -5. Work out the value of a.