Mathematics: F(x)=7x+3 and g(x)=-6x-8, find (f•g)(x) and (f•g)(-1)

F(x)=7x+3 and g(x)=-6x-8, find (f•g)(x) and (f•g)(-1)

naomicervero

27.01.2022

(f*g)(x)=-42x^2-74x-24

(f*g)(-1)=8

Step-by-step explanation:

$f(x)=7x+3\\ g(x)=-6x-8$

$(f*g)(x)=(7x+3)(-6x-8)\\(f*g)(x)=-42x^2-56x-18x-24\\(f*g)(x)=-42x^2-74x-24$

Now;

$(f*g)(-1)=-42x^2-74x-24\\(f*g)(-1)=-42(-1)^2-74(-1)-24\\(f*g)(-1)=-42(1)+74-24\\(f*g)(-1)=-42+50\\(f*g)(-1)=8$

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kate8941

06.05.2022

Step-by-step explanation:

Let the distance be d and average speed be v.

Half of the distance the speed was 2/3v

Let the speed be xv in the second half of the distance.

Then time is:

d/v = d/2 : (2/3v) + d/2 : (xv)d/v = 3/4(d/v) + (1/2x)(d/v)1 = 3/4 + 1/2x1/2x = 1 - 3/4 1/2x = 1/42x = 4x = 2

The rest of the road car has to ride with speed of 2v

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