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3 years ago

If a^2-b^2=15 and (a-b)=7 what is the value of(a+b)

1 answer:

3 0

$\bf \textit{difference of squares} \\\\ (a-b)(a+b) = a^2-b^2 \\\\[-0.35em] ~\dotfill\\\\ a^2-b^2=15\implies (a-b)(a+b)=15\implies \stackrel{\stackrel{a-b}{\downarrow }}{(7)}(a+b)=15\implies a+b=\cfrac{15}{7}$

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In a box there are six envelopes each containing two cards. Three of the envelopes contain two red cards, two of them contain a

Sphinxa [80]

Answer:

$\frac{2}{5}$

Step-by-step explanation:

3 envelopes having 2 red card

2 envelopes having 1 red card and 1 black card

1 envelope having 2 black cards

We are given that . An envelope is selected at random and a card is withdrawn and found to be red.

So, No. of ways of envelope having red card = 3+2 = 5

No. of required ways of envelope having 1 red card and 1 black card = 2

So, probability of getting an envelope having 1 red card and 1 black card = $\frac{2}{5}$

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3 years ago

Factor completely 15x^5 + 12x^4-24x^3-3x^2

diamong [38]

Answer:

3x^2 (5x^3 + 4x^2 - 8x - 1)

Step-by-step explanation:

The given expression is 15x^5 + 12x^4-24x^3-3x^2

Here we have to find the GCF of all the above terms.

The GCF is 3x^2, let's take out 3x^2 and write the remaining terms in the parenthesis.

15x^5 + 12x^4-24x^3-3x^2

=3x^2 (5x^3 + 4x^2 - 8x - 1)

Therefore, the factors are 3x^2 and (5x^3 + 4x^2 -8x -1).

15x^5 + 12x^4-24x^3-3x^2 = 3x^2 (5x^3 + 4x^2 -8x -1)

Thank you.

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Answer:

Step-by-step explanation:

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