Please help
What are the roots (zeros) of the polynomial f(x)=x^3+3x^2-9x+15

9514 1404 393

  {-5.2555, 1.1278 ± 1.2579i}

Step-by-step explanation:

Descarte's rule of signs tells you there are 0 or 2 positive real roots and 1 negative real root. A graph shows you the negative roots is irrational, and the positive roots are complex.

There are formulas for solving equations of this sort. The method you use will depend on whether you need an exact result or just a numerical approximation. Exact results can be obtained in terms of radicals or in terms of trig functions.

The first attachment is from a freely available solver. It gives 4 decimal places, which is sufficient for many purposes.

The second attachment is the graph, along with the quadratic that results from dividing f(x) by the factor that gives the real root. While the values shown on the graph are to 3 decimal places, the calculator can be used to find them to greater precision. (We have used Newton's Method iteration to find the real root to 12 significant figures.)

∠acb = 8°

step-by-step explanation:

∠xba lies on the circle and is half the measure of the intercepted arc ax

hence

measure of arc ax = 2 × 42° = 84°

∠acb is outside the circle and is

∠acb = (arcab - arcax ), hence

∠acb = 0.5 (100 - 84) = 0.5 × 16° = 8°

answer: c, the green line

step-by-step explanation:

there is no black line, eliminate b.

simple interest implies periodic payments, but the red line shows no payments, eliminate d.

simple interest has equal payments. if paid say every day, the graph is about a straight line (actually a stairstep).

the yellow line is not straight, eliminate a.

check: the green line is straight, answer is c.

simple interest with positive interest rate gives a straight line sloping up to the right. green line:

g(t) = $100 + ($200-$100) ÷ (20 years) × (t years)

= $100 + (4%/year) × ($100)(t years)

incidentally, the yellow line curving upward represents continuously compounded interest

y = $100 × 2^(t years / (14 assuming the yellow line hits $200 at 14 years. 2^0 is 1, so y(0) = $100; 2^(14/14) is 2, so y(14) = $200.