Mathematics, 27.01.2020 06:31 iBrain

It is known that x1 and x2 are roots of the equation $6x^{2} +7x+k=0$
, where $2x_{1} +3x_{2} =-4$ . find k.

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Answer from: kland5460

k=-5

Step-by-step explanation:

we know that

The formula to solve a quadratic equation of the form

$ax^{2} +bx+c=0$

is equal to

$x=\frac{-b\pm\sqrt{b^{2}-4ac}} {2a}$

in this problem we have

$6x^{2} +7x+k=0$

$a=6\\b=7\\c=k$

substitute in the formula

$x=\frac{-7\pm\sqrt{7^{2}-4(6)(k)}} {2(6)}\\\\x=\frac{-7\pm\sqrt{49-24k}} {12}$

$x_1=\frac{-7+\sqrt{49-24k}} {12}\\\\x_2=\frac{-7-\sqrt{49-24k}} {12}$

Remember that

2x_1+3x_2=-4

substitute

$2(\frac{-7+\sqrt{49-24k}} {12})+3(\frac{-7-\sqrt{49-24k}} {12})=-4\\\\(\frac{-14+2\sqrt{49-24k}} {12})+(\frac{-21-3\sqrt{49-24k}} {12})=-4$

Multiply by 12 both sides

$(-14+2\sqrt{49-24k})+(-21-3\sqrt{49-24k})=-48\\\\-35-\sqrt{49-24k}=-48\\\\\sqrt{49-24k}=48-35\\\\\sqrt{49-24k}=13$

squared both sides

$49-24k=169\\24k=49-169\\24k=-120\\k=-5$

therefore

The equation is

$6x^{2} +7x-5=0$

The roots are

$x=\frac{-7\pm\sqrt{49-24(-5)}} {12}\\\\x=\frac{-7\pm\sqrt{169}} {12}\\\\x=\frac{-7\pm13} {12}\\\\x_1=\frac{-7+13} {12}=\frac{1} {2}\\\\x_2=\frac{-7-13} {12}=-\frac{5} {3}$

Answer from: Quest

d. 8

step-by-step explanation:

the given radical expression is:

$\sqrt{16}\times \sqrt{4}$

we can rewrite this as:

$(16)^{\frac{1}{2}\times (4)^{\frac{1}{2}$

we express as square numbers to get;

$(4^2)^{\frac{1}{2}\times (2^2)^{\frac{1}{2}$

the exponents will now cancel out to give.

$4\times2=8$

the correct answer is d

What is the value of the radical expression shown below

Answer from: Quest

ratios represent a pattern or relationship that can be scaled.

equivalent ratios are pairs of ratios that represent the same relationship between quantities, and can be generated by multiplying or dividing both quantities in the ratio by the same factor.

in this lesson, students will use double number lines and ratio reasoning to solve ratio problems. by partitioning double number lines into proportionate intervals, students will build an understanding of equivalent ratio relationships as those that are generated by multiplying or dividing two related quantities by the same number. this lesson will build upon students' prior understanding of multiplicative comparisons, number line reasoning and equivalent fractions (while highlighting the difference between equivalent fractions and equivalent ratios); and will build toward future work in this unit on building ratio tables, and work in future grades in proportionality, scaling, and expressing and graphing linear functions.

step-by-step explanation:

ratios represent a pattern or relationship that can be scaled.

equivalent ratios are pairs of ratios that represent the same relationship between quantities, and can be generated by multiplying or dividing both quantities in the ratio by the same factor.

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It is known that x1 and x2 are roots of the equation [tex]6x^{2} +7x+k=0[/tex]
, where [tex]2x...

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