Simplify: (x+7)(x-4)

Mathematics

1 answer:

SVETLANKA909090 [29]3 years ago

6 0

Answer:

x² + 3x - 28

Step-by-step explanation:

Each term in the second factor is multiplied by each term in the first factor

(x + 7)(x - 4)

= x(x - 4) + 7(x - 4) ← distribute both parenthesis

= x² - 4x + 7x - 28 ← collect like terms

= x² + 3x - 28

You might be interested in

Cos(-170°) = _____<br><br> -cos10°<br> cos10°<br> cos(-10°)

ikadub [295]

<em>The right answer for:</em>

<h2>Explanation:</h2>

The cosine function is an even function, which means that for every point $(x,y)$ on the graph of $y=cos(x)$ then the point $(-x,y)$ also lies on the graph of the function. In other words, we can write:

$cos(-170^{\circ})=cos(170^{\circ})$

But:

$170^{\circ}=180^{\circ}-10^{\circ}$

So:

$cos(170^{\circ})=cos(180^{\circ}-10^{\circ})$

By property:

$cos(a-b)=cosacosb+sinasinb \\ \\ a=180^{\circ} \\ \\ b=10^{\circ} \\ \\ cos(170^{\circ} )=cos(180^{\circ} -10^{\circ})=cos180^{\circ} cos10^{\circ} +sin180^{\circ} sin10^{\circ} \\ \\ cos(170^{\circ})=-cos(10^{\circ})+0 \\ \\ \boxed{cos(170^{\circ})=-cos(10^{\circ})}$