Question

The functions q and r are defined as follows.

q(x) = -2x +1
r(x) = 2x^2 - 1
Find the value of .
q(r(4))

Answer 1

The value of q( r(4) ) = -61

Explanation:

It is given that,

q(x) = - 2x +1

r(x) = 2x^2 - 1

To find the value of q(r(4))

r(x) = 2x^2 - 1

r(4) = 2( 4^2) - 1 [Substitute 4 instead of x]

= 2(16) - 1

= 32 - 1 = 31

q( x ) = -2x +1

q( r(4) ) = q(31) [Substitute 31 instead of x)

= (-2*31) +1

= -62 + 1 = -61

Therefore the value of q(r(4)) = -61

Answer 2

q(r(4)) = -61

Explanation:

q(x) = -2x +1

r(x) = 2x^2 - 1

q(r(4))

First find r(4)

f(4) = 2 (4)^2 -1

= 2 *16 -1

= 32-1

= 31

Then put this value in for x in q(x)

q(r(4)) = q(31) = -2(31)+1

= -62+1

= -61