The square of Mark's age 3 years ago is 6 times the age he will be in 9 years. What is his age now?

Mathematics

2 answers:

9966 [12]3 years ago

5 0

Answer:

15.

Step-by-step explanation:

Let his age now be x years. Then:

(x - 3)^2 = 6(x + 9)

x^2 - 6x + 9 = 6x + 54

x^2 - 12x - 45 = 0

(x - 15)(x + 3) = 0

x = 15, -3

We ignore the negative so his age now is 15.

Lubov Fominskaja [6]3 years ago

3 0

Answer:

Age= 15

Step-by-step explanation:

Let a be for age at the moment

(a-3)^2 =6(a+9)

a^2-6a+9=6a+54

a^2-12a-45

(a-15)(a+3)

a=15 or a=-3

Age cannot be negative (-)

Therefore

Age =15

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kati45 [8]

We are given that revenue of Tacos is given by the mathematical expression $-7x^{2}+32x+240$ .

(A) The constant term in this revenue function is 240 and it represents the revenue when price per Taco is $4. That is, 240 dollars is the revenue without making any incremental increase in the price.

(B) Let us factor the given revenue expression.

$-7x^{2}+32x+240=-7x^{2}+60x-28x+240\\-7x^{2}+32x+240=x(-7x+60)+4(-7x+60)\\-7x^{2}+32x+240=(-7x+60)(x+4)\\$

Therefore, correct option for part (B) is the third option.

(C) The factor (-7x+60) represents the number of Tacos sold per day after increasing the price x times. Factor (4+x) represents the new price after making x increments of 1 dollar.

(D) Writing the polynomial in factored form gives us the expression for new price as well as the expression for number of Tacos sold per day after making x increments of 1 dollar to the price.

(E) The table is attached.

Since revenue is maximum when price is 6 dollars. Therefore, optimal price is 6 dollars.