McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
6. Common Logarithms
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Exercise 85 Page 498

Use the formula for the area of a triangle.

32x^3+8x^2-24x+16 meters

Practice makes perfect

The area of a triangle is calculated by taking half the product of the base b and the height h. A= 12 b hIn our case, the area of a triangular sail is 16x^4-60x^3-28x^2+56x-32 square meters, and its base is x-4 meters. We are asked to find the height of the sail. Let's substitute the expressions into the formula for the area and solve it for h.

A= 12 b h
16x^4-60x^3-28x^2+56x-32= 12 (x-4) h
â–¼
Solve for h
32x^4-120x^3-56x^2+112x-64=(x-4)h
32x^4-120x^3-56x^2+112x-64/x-4=h
h=32x^4-120x^3-56x^2+112x-64/x-4

Now, we want to divide two polynomials. You can use polynomial long division or a synthetic division. After the division, we get the following. h=32x^4-120x^3-56x^2+112x-64/x-4 ⇓ h= 32x^3+8x^2-24x+16 Therefore, the height of the sail is 32x^3+8x^2-24x+16 meters.

Extra

Synthetic Division
We will show how to divide 16x^4-60x^3-28x^2+56x-32 by x-4 using polynomial synthetic division. Remember that the general form of the synthetic division divisor must be x-a. Since the given divisor is already written in this form, we are ready to go.

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 & & & & & c

Bring down the first coefficient

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 & & & & & c 32

Multiply the coefficient by the divisor

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & & & & c 32

Add down

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & & & & c 32 8
â–¼
Repeat the process for all of the coefficients

Multiply the coefficient by the divisor

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & 32 & & & c 32 8

Add down

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & 32 & & & c 32 8 - 24

Multiply the coefficient by the divisor

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & 32 & - 96 & & c 32 8 - 24

Add down

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & 32 & - 96 & & c 32 8 - 24 16

Multiply the coefficient by the divisor

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & 32 & - 96 & 64 & c 32 8 - 24 16

Add down

rl IR-0.15cm r 4 & |rr 32 &- 120 &- 56& 112 &- 64 &128 & 32 & - 96 & 64 & c 32 8 - 24 16 0

The quotient is a polynomial of degree 3, with the above coefficients. The remainder is 0. Quotient & Remainder 32x^3+8x^2-24x+16 & 0 Therefore, our expression can be written in the following form. 32x^4-120x^3-56x^2+112x-64/x-4 ⇕ 32x^3+8x^2-24x+16