Question

2r2 + 3s3 − r2 + 4t2 − r2 if r = −2, s = −3, and t = 5.

Answer 1

19

Explanation:

Given the formula:

2r^2 + 3s^3 − r^2 + 4t^2 − r^2

Replace with these values r = −2, s = −3, and t = 5 and compute the result.

2(-2)^2 + 3(-3)^3 − (-2)^2 + 4(5)^2 − (-2)^2 =

= 2*4 + 3*(-27) - 4 + 4*25 - 4 =

= 8 - 81 - 4 + 100 - 4 =

= 19

Answer 2

First, simplify the expression
`2r^2 + 3s^3 - r^2 + 4t^2 - r^2.` Here you have three terms with
`r^2,` group them in the following way:

`2r^2 + 3s^3 - r^2 + 4t^2 - r^2=2r^2-r^2-r^2+3s^3+4t^2=(2r^2-r^2-r^2)+3s^3+4t^2=`

`=r^2(2-1-1)+3s^3+4t^2=3s^3+4t^2.`

Then substitute s=-3 and t=5:

`3s^3+4t^2=3\cdot (-3)^3+4\cdot 5^2=3\cdot (-27)+4\cdot 25=-81+100=19.`

Answer: 19.