Mathematics, 24.02.2020 18:56, kris7726

Let f(x)=2x^2 + 5x – 7 and g(x)=x-1 Perform the function operation and then find the domain.
(f+g)(x)

Answers: 3

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answered: Goodgirlkl12k

2x^2+6x-8 , domain: all real numbers

Step-by-step explanation:

The two functions that we have in this problem are:

f(x)=2x^2+5x-7

and

g(x)=x-1

Here we have to calculate

(f+g)(x)

Which is equivalent to:

(f+g)(x)=f(x)+g(x)

Taking the two functions and substituting into this expression, we find:

(f+g)(x)=(2x^2+5x-7)+(x-1)=2x^2+6x-8

We also have to find the domain of the new function. However, we notice that there are no restrictions on the value of x, since this is a second-order function with no denominators, logarithms or roots: therefore, the domain is all real numbers.

answered: Guest

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84 (as 9^2 = 9*9 = 81)

which is the second choice

regards,

mrb

p.s. i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!

answered: Guest

starting with:

5 + x - 12 = 2x - 7

5 + x - 12 - x = 2x - 7 - x (subtract x from both sides)

5 - 12 = x - 7 (combine and cancel x's from both sides)

5 - 12 + 7 = x - 7 + 7 (add 7 to both sides)

0 = x (add numbers together on both sides)

so in order for the equation to be true, x must be 0.

trying x = -0.5

5 + x - 12 = 2x - 7 (original equation)

5 + -0.5 - 12 = 2(-0.5) - 7 (plug in value of x)

5 + -0.5 - 12 = -1 - 7 (did multiplication)

-7.5 = -8 (did addition on both sides)

since -7.5 is obviously not equal to -8, the value of -0.5 for x is wrong.

trying x = 0

5 + x - 12 = 2x - 7 (original equation)

5 + 0 - 12 = 2(0) - 7 (plug in value of x)

5 + 0 - 12 = 0 - 7 (did multiplication)

-7 = -7 (did addition on both sides)

since -7 equals -7, that demonstrates that the value of 0 for x is correct.

trying x = 1

5 + x - 12 = 2x - 7 (original equation)

5 + 1 - 12 = 2(1) - 7 (plug in value of x)

5 + 1 - 12 = 2 - 7 (did multiplication)

-6 = -5 (did addition on both sides)

since -6 is obviously not equal to -5, the value of 1 for x is wrong.

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Let f(x)=2x^2 + 5x – 7 and g(x)=x-1 Perform the function operation and then find the domain.
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