(a) Write each answer as an equality, and any decimals up to 7 decimal places. C

sodni3

sodni3

Answered question

2021-09-09

(a) Write each answer as an equality, and any decimals up to 7 decimal places. Clearly state the value of and δ(orMorNandδ) in each case.
(i) How close to 4 do we need to take x so that (x22)<0.001 ?
(ii) How close to 4 do we need to take x so that (x22)>0.0001 ?
(iii) How close to 0 do we need to take x so that (2x+9)<9.0001 ?
(iv) How close to 0 do we need to take x so that (2x+9)>8.999?
(v) How close to 0 do we need to take x so that (x2+6x+9)<9.001 ?
(vi) How close to 0 do we need to take x so that (x2+6x+9)<9.0001 ?
(vii) How close to 0 do we need to take x so that (x2+6x+9)>8.9999 ?
(viii) How close to -7 do we need to take x so that 1(x+7)4>10000 ?
(ix) How close to −7 do we need to take x so that 1(x+7)4>100000 ?
(x) How close to 0 do we need to take x so that lnx<10000?
(b) Use the definition of a limit to show that
(i) limx4
(x22)=0
(ii) limx0
(2x+9)=9
(iii) limx0
(x2+6x+9)=9
(iv) limx7
1(x+7)4=
(v) limx0+
lnx=

Answer & Explanation

Raheem Donnelly

Raheem Donnelly

Skilled2021-09-10Added 75 answers

Step 1
"Since you have posted a question with multiple sub-parts, we will solve first four sub-parts for you. To get remaining sub-part to be solved please re-post the complete question and mention the sub-parts to be solved".
a. (i) How close to 4 do we need to take x so that (x22)<0.001 ?
Let the inequality be x22<0.001
x22<0.001
x2<0.001+2
x<2.001(2)
x<4.002
x should be close to 4 by 0.002 so that x22<0.001
Step 2
(ii) How close to 4 do we need to take x so that (x22)>0.0001 ?
Let the inequality be x22>0.0001
x22>0.0001
x2>0.0001+2
x>2.0001(2)
x>4.0002
x should be close to 4 by 0.0002 so that x22>0.0001
Step 3
(iii) How close to 0 do we need to take x so that (2x+9)<9.0001 ?
Let the inequality be (2x+9)<9.0001
(2x+9)<9.0001
2x<9.00019
2x<0.0001
x<0.00005
x should be close to 0 by 0.00005 so that (2x+9)<9.0001
Step 4
(iv) How close to 0 do we need to take x so that (2x+9)>8.999?
Let the inequality be (2x+9)>8.999
(2x+9)>8.999
2x>8.9999
2x0.001
x0.0005
x should be close to 0 by - 0.0005 so that (2x+9)>8.999

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