Math Is Fun Forum

Write the expression in the standard form a + bi.

6i^3 + 4i^5

A student's average (arithmetic mean) test score on 4 tests is 78. What must be the student's score on a 5th test for the student's average score on the 5 tests to be 80?

Step 1
Mult.both sides by 4+t, assuming 4+t≠0

Make t the subject of the formula

p=(3-2t)/(4+t)

The left hand side was given in the traditional fraction form, with numerator on top of denominator; this is just the same, yeah, with the slash?

Here's my attempt;

Step 1
Mult.both sides by 4+t;
p(4+t)=3-2t
Step 2
Expand brackets;
4p+pt=3-2t
Step 3
Sub.4p from both sides;
pt=3-2t-4p
Step 4
Add 2t to both sides;
pt+2t=3-4p
Step 5
Factorise left side;
t(p+2)=3-4p
Step 6
Divide both sides by (p+2);
t=3-4p/p+2

May I add...

sqrt{(a + b)^2} = ±(a + b)

like sqrt{(1 + 2)^2} = sqrt(9) = ±3

[addressed to KerimF] actually, sqaure root is defined to be the positive answer

Yeah, no kidding. Where is your math work? Seriously, I personally don't want to read a story about each problem posted. Just do the math. Get it?

Solve 1/a = 1/b + 1/c

I’ve come across questions recently that go something as follows;
Tom invests £2000 for 3 years.
For the first year he gets 3% compound interest...
Then for the next two years he gets x% compound interest. Etc.
I’ve been managing to get the correct answer, but the idea of someone receiving compound interest ‘for the first year’ seems strange to me.
Compound interest by it’s definition seems to me to only make sense if someone receives it for 2 or more years. If they are said to get it for ‘the first year,’ i.e, for 1 year, how does this differ from them getting simple interest for 1 year?
£2000. Compound interest. 3%. 1 year. Savings at the end of 1 year = £2060
£2000. Simple interest. 3%. 1 year. Savings at the end of 1 year = £2060

Is that correct?

A circular pool measures 10 feet across. One cubic yard of concrete is to be used to create a circular border of uniform width around the pool. If the border is to have a depth of 3 inches, how wide will the border be?

looking forward to seeing the answer.

hi amnkb

Yes, I did that too. But it doesn't tell what k is.  There must be more to this question

Show that the real solutions of the equation ax^2 + bx + c = 0 are the negatives of the real solutions of the equation ax^2 - bx + c = 0. Assume that b^2 - 4ac is greater than or equal to 0.

Just answer the questions posted and keep your text math-related.

The screen size of a TV is determined by the length of the diagonal of the rectangular screen. Traditional TVs come in a 4 : 3 format, meaning the ratio of the length to the width of the rectangular screen is 4 yo 3.

A. What is the area of a 37-inch traditional TV screen?

B. What is the area of a 37-inch LCD TV whose screen is in a 16 : 9 format. Which screen is bigger?

Just answer the questions posted and keep your text math-related.

A lanscaper, who just completed a rectangular flower garden measuring 6 feet by 10 feet, orders 1 cubic yard of premixed cement, all of which is to be used to create a border of uniform width around the garden. If the border is to have a depth 3 inches, how wide will the border be?

Just answer the questions posted and keep your text math-related.