If a = -12 and b = -14 then 2a + 2b + 3 is
Answer: B
Substitute \( a = -12 \) and \( b = -14 \).
\[ 2a = -24, \qquad 2b = -28 \]
\[ -24 - 28 + 3 = -49 \]
Both doubled values stay negative; the \( +3 \) only softens the total slightly.
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Which of the following is the numerical coefficient of x²y²?
Answer: A
The numerical coefficient is the number multiplying the variable part. Written in full, the term is
\[ x^{2}y^{2} = 1 \cdot x^{2}y^{2} \]
so the coefficient is 1. \( x^{2} \) and \( y^{2} \) are parts of the variable factor, not numbers.
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If the expression \( 4c + 4b + 4d \) is subtracted from \( 3c + 4b + 5d \), then the answer will be
Answer: A
Subtracting flips every sign in the expression being taken away.
\[ (3c + 4b + 5d) - (4c + 4b + 4d) \]
\[ = (3c - 4c) + (4b - 4b) + (5d - 4d) \]
\[ = -c + d \]
The \( b \) terms cancel exactly, which is why no \( b \) survives.
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If 6x + 2y - 4z is subtracted from 2x - 8y + 5z then answer will be
Answer: D
Subtracting flips every sign in the second expression.
\[ (2x - 8y + 5z) - (6x + 2y - 4z) \]
\[ = 2x - 8y + 5z - 6x - 2y + 4z \]
\[ = -4x - 10y + 9z \]
The \( -4z \) becomes \( +4z \), which is what makes the \( z \) coefficient \( +9 \).
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The value of x² - 5 at x= -1 is -
Answer: C
Substitute \( x = -1 \), squaring before subtracting.
\[ x^{2} - 5 = (-1)^{2} - 5 = 1 - 5 = -4 \]
A negative number squared is positive, so \( (-1)^{2} = 1 \), not \( -1 \) - that slip would give \( -6 \).
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In 15y and 160ab, coefficients are
Answer: D
The coefficient is the numerical factor of a term.
\[ 15y \rightarrow 15, \qquad 160ab \rightarrow 160 \]
The letters \( y \), \( a \) and \( b \) are the variable parts, not coefficients.
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Algebraic expression of difference of 13x and 7y can be written as
Answer: B
"Difference of 13x and 7y" means the first minus the second.
\[ 13x - 7y \]
The two terms are unlike, so the subtraction cannot be carried out any further - \( 6xy \) would come from subtracting the coefficients and merging the variables, which is not a valid step.
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Algebraic form of statement "sum of product of 2a and 2b and product of 12x and 2y" is
Answer: A
Form each product, then add them.
\[ 2a \times 2b = 4ab \]
\[ 12x \times 2y = 24xy \]
\[ \therefore\ 4ab + 24xy \]
Both coefficients multiply within their own product; the two products are then joined by addition, not multiplied together.
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By factorizing algebraic expression cx + cy - dx - dy, answer will be
Answer: A
Group in pairs and factor each.
\[ cx + cy - dx - dy = c(x + y) - d(x + y) \]
\[ = (c - d)(x + y) \]
Taking out \( -d \) from the second pair turns \( -dx - dy \) into \( -d(x+y) \), matching the first bracket.
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On solving expression 6a + 8b - 11a, answer will be
Answer: A
Only the \( a \) terms are alike.
\[ 6a - 11a = -5a \]
\[ \therefore\ -5a + 8b \]
Since \( 11 > 6 \), the result is negative; the \( 8b \) is unlike and stays put.
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