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Solve x^2 + 15x = - 50

x 2 + 15 x + 50 = 0 (rearrange by adding 50 to both sides) (x + 10)(x + 5) = 0 (factorise the quadratic equation) x + 10 = 0 or x + 5 = 0 (for the above to equal zero, at least one of the bracketed terms mus...
JS
Answered by Julia S. • Maths tutor
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In one experiment, the temperature of 50 g of water increased from 22.0 °C to 38.4 °C. The mass of alcohol burned was 0.8 g. Calculate the heat energy (Q) in joules, released by burning 0.8 g of the alcohol.

Key Equation: Q = mc ΔT Where: Q = heat transferred (J), m = mass of substance which is heated (g), c = heat capacity of water (J g -1 °C -1 ) and ΔT = temperature change for heated substance (°C) . c = 4.2 ...
DB
Answered by David B. • Chemistry tutor
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f(x) = 2x + c, g(x) = cx + 5, fg(x) = 6x + d. c and d are constants. Work out the value of d. 3 marks.

fg(x) = 2(cx+5) + c = 2cx+10+c [1 mark] fg(x) = 6x+d. fg(x) = 2cx+10+c 6x = 2cx and d = 10+c [2 marks] 3 = c and therefore d = 13 [3 marks]
HK
Answered by Heba K. • Maths tutor
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balance equation : PCl5 + 4H2O → H3PO4 + HCl

fist look at the first molecule on the left of the equation, the first atom is P there's 1 mole and looking at the right there is also only one. the look at the next atom Cl which has five mole, on the right...
CM
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What is the general equation for a straight graph line and what does each part represent?

Y= mX + c, 'X' is the horizontal value on the axis, the input value. The 'm' represents the gradient of the line, figured out by the change in y divided by the change in x. The 'c' value is the y intercept, ...
TW
Answered by Toby W. • Maths tutor
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