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A student titrated a solution of 25 cm3 of NaOH of concentration 0.1 mol/dm3 with H2SO4. She achieved four results; 25.8 cm3, 26.15 cm3, 26.25 cm3 and 26.45 cm3. Calculate the concentration of H2SO4 using concordant titres.

H₂SO₄ + 2NaOH → Na₂SO₄+ 2H₂O
Concordant titres: 26.15 cm³ and 26.25 cm³
Mean titre: (26.15+26.25)/2= 26.2 cm^3...

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Solve n^2+n-90=0 to find the value of n?

Using the quadratic formula with a calculator a=1 b=1 c=-90 answers are n=-10 and n=9Factorising (n-9)(n+10)=0 answers are n=-10 and n=9

Answered by Asher L. • Maths tutor

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Consider the curve y=x/(x+4)^0.5. (i) Show that the derivative of the curve is given by dy/dx= (x+8)/2(x+4)^3/2 and (ii) hence find the coordinates of the intersection between the left vertical asymptote and the line tangent to the curve at the origin.

The unsimplified form of the derivative can be obtained fairly easily with use of the quotient rule. The trick for simplification is to multiply top and bottom by (x+4)^0.5, this allows manipulation of th...

Answered by Seb R. • Maths tutor

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Integrate 3x^4-4x^2+3/x

Firstly, integrate each term individually, starting off with the 3x^4. In order to integrate the index on the x term needs to be raised by 1, and the coefficient of the x should be divided by this new val...

Answered by Muhammad R. • Maths tutor

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Vous écrivez un article sur la qualité des collèges en Grande-Bretagne pour un magazine français. Décrivez : • pourquoi votre collège est un bon collège • un événement scolaire mémorable. Ecrivez environ 150 mots en français.

Mon collège est petit mais très beau. J’aime la plupart des profs parce qu’ils sont gentils et parfois drôles. De plus, les cours sont très intéressants. Ma matière préférée est la technologie parce qu’on...

Answered by Anna S. • French tutor

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