Bac Séries F Côte d'Ivoire - independent subject practice common mistakes
Bac Séries F Côte d'Ivoire - independent subject practice · Understand the traps and how to avoid them.
Treating a model calculation as physical operating authorization.
The model omits equipment, legal and practical conditions.
What to do instead
State its classroom scope and obtain actual approved procedures before implementation.
Mixing energy with power.
Rates and totals have different dimensions.
What to do instead
Write units and multiply power by time only under a stated time model.
Using a display’s smallest increment as its accuracy.
Resolution does not measure bias, calibration or total uncertainty.
What to do instead
Read the instrument specification and include relevant uncertainty sources.
Applying a formula outside its stated assumptions.
Memorized expressions can hide geometry, waveform or operating restrictions.
What to do instead
State assumptions and test whether the supplied scenario satisfies them.
Confusing a supplied allowable stress with yield strength.
An allowable limit can incorporate other criteria and margins.
What to do instead
Identify the definition of each stated limit before calculating a ratio.
Ignoring losses in an output calculation.
Ideal input-output relations do not automatically apply to real devices.
What to do instead
Apply the specified efficiency once in the correct direction and check the energy balance.
Comparing lifecycle totals for different services.
Different functional units can make the ranking meaningless.
What to do instead
Normalize the service, boundary and time horizon before comparing impacts.
Reading an obsolete drawing as the current design.
A technically plausible dimension can belong to the wrong revision.
What to do instead
Check drawing identifiers, revision status and linked parts before calculating.
Treating a single good test result as complete approval.
A test samples particular properties under particular conditions.
What to do instead
Match each requirement to the evidence it needs and identify untested conditions.
Rounding intermediate values too early.
Accumulated rounding can change the final comparison.
What to do instead
Retain appropriate guard digits and round at the final reporting precision.
When differentiating a composite function, the candidate differentiates only the outer function and drops the inner derivative - writing d/dx sin(3x²) = cos(3x²) or d/dx e^(x²) = e^(x²).
Chain rule is learned as a pattern ('derivative of sin is cos') and under timed conditions the candidate pattern-matches the outer function and stops, treating the argument as a single variable. Nested functions with polynomial or exponential inner parts are where the omission is most likely, because the inner derivative is not visually salient.
What to do instead
Before writing any answer, explicitly name the inner function u and write the chain as outer′(u)·u′ on the page, even for one-line answers. Drill a mixed set of 20 composites (trig, exponential, log, power, inverse trig) and mark each inner derivative in a different colour until the step becomes automatic. On the exam, do a final pass over every derivative checking that each composite has a visible inner-derivative factor.
The candidate computes a definite integral or area but substitutes the limits in the wrong order or forgets to change limits after substitution, producing a sign-flipped or wrong-valued answer, e.g. evaluating ∫₀² with F(0) − F(2).
The upper-minus-lower convention competes in memory with the substitution rule's 'evaluate at old limits', and under pressure the candidate writes the antiderivative values in the order they appear on the page. When using u-substitution the candidate often back-substitutes inconsistently or plugs original limits into the u-antiderivative.
What to do instead
Adopt a fixed written template: bracket the antiderivative, write '= [F(x)]_a^b = F(b) − F(a)', and physically copy b above a before evaluating. For substitution, always either convert the limits to u-values in the same line or write 'back-substitute to x, then apply original limits' - never mix. Practise five substitution integrals where the limits are converted, checking that a positive integrand gives a positive result.