-7x+6y=34 7x+4y=-24 helppp

Mathematics

1 answer:

Alja [10]3 years ago

5 0

Answer:

x=–4, y=1

Step-by-step explanation:

adding the 2 equations, we see the X's go away and we are left with: 10y=10. we can simplify and solve for y by dividing both sides by 10 and we are left with y=1

plugging 'y=1' into the fist equation we get: -7x+6=34. we can now solve for x by subtracting 6 from both sides and dividing both side by –7, so we are left with: x=–4

we can check by plugging both x and y into one of the original equations:

-7(-4)+6(1)=34

28+6=34

34=34✓

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Six identical squares are cut from the corners and edges of an 80 cm by 50 cm cardboard rectangle. the remaining piece is folded

Anna11 [10]

Check the picture.

let the length of a side of each of the squares removed be x.

The box formed will have dimensions: 80-2x, 50-2x, x(the height)

So the volume can be expressed as a function of x as follows:

f(x)=(80-2x)(50-2x)x= $[4000-160x-100x+4 x^{2} ]x=(4 x^{2}-260x+4000)x$

so $f(x)=4 x^{3}-260x^{2}+4000x$

the solutions of f'(x)=0 gives the inflection points, so the candidates for maxima points,

$f'(x)=12x^{2}-520 x +4000=0$

solving the quadratic equation, either by a calculator, graphing software, or by other algebraic methods as the discriminant formula, we find the solutions

x=10 and x=33.333

plug in f(x) these values to see which greater:

$f(10)=(80-20)(50-20)10=60*30*10=18000$ cm cubed

$f(33.333)=(80-66.666)(50-66.666)33.333=$ which is negative because (50-66.666)<0

Answer: 18000 cm cubed