Find f(-2) for the function f(x)= 3x2-2x+7

Mathematics

1 answer:

4vir4ik [10]3 years ago

4 0

Answer:

f( - 2) = 23

Step-by-step explanation:

$f(x) = 3 {x}^{2} - 2x + 7 \\ plug \: x = - 2 \\ f( - 2) = 3 {( - 2)}^{2} - 2( - 2)+ 7 \\ = 3 \times 4 + 4 + 7 \\ = 12 + 11 \\ \huge \red{ \boxed{ f( - 2) = 23}}$

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5+2 root 3 / 7+4 root 3 =a-6root3

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Answer:

Step-by-step explanation:

$\dfrac{5+2\sqrt3}{7+4\sqrt3}\qquad\text{use}\ (a+b)(a-b)=a^2-b^2\\\\=\dfrac{5+2\sqrt3}{7+4\sqrt3}\cdot\dfrac{7-4\sqrt3}{7-4\sqrt3}=\dfrac{(5+2\sqrt3)(7-4\sqrt3)}{7^2-(4\sqrt3)^2}\qquad\text{use FOIL}\\\\=\dfrac{(5)(7)+(5)(-4\sqrt3)+(2\sqrt3)(7)+(2\sqrt3)(-4\sqrt3)}{49-4^2(\sqrt3)^2}\\\\=\dfrac{35-20\sqrt3+14\sqrt3-8(3)}{49-(16)(3)}=\dfrac{(35-24)+(-20\sqrt3+14\sqrt3)}{49-48}\\\\=\dfrac{11-6\sqrt3}{1}=11-6\sqrt3$