mathematics question :(

POP222 SG

Hi! Can someone help me solve this question? I have the answer but i dont understand the steps so i need someone to help me with the solutions step by step. The question is:

Given that (2x – 1)(x + m) = 2x² + nx – 3, find the value of

a) m

b) n

I really need someone to help me asap! thank you.

wee_ws SG

Hi,

1. Expand the LHS expression.

2. To find m, compare the constants in the LHS and RHS expressions.

3. To find n, compare the coefficients of x in the LHS and RHS expressions.

Thanks.

Cheers,
Wen Shih

POP222 SG

sorry but how do you compare the constants and coefficients? i dont really get the second and third step.

wee_ws SG

Hi,

Let's say x^2 - px + 7 = x^2 + 4x - q, we will then conclude that

1. -p = 4 by comparing the coefficients of x on both sides,

2. -q = 7 by comparing the constants on both sides.

Thanks.

Cheers,
Wen Shih

POP222 SG

can you explain the meaning of coefficient and constants?

and do you know what topic is this question under?

eagle SG

ax^2 + bx + c

a is a coefficient of x^2

b is a coefficient of x

c is a constant

This is probably under the topic of quadratic equations?

POP222 SG

then for my question, how do i find the value of n? I dont know how to get the asnwer for that question still.

wee_ws SG

Hi,

To find n, you will need the value of m. Thanks.

Cheers,
Wen Shih

eagle SG

Hi POP,

I hope you understand that we are trying to guide you instead of spoonfeeding the answer.

It's the hols and I assure you that you will improve greatly if you can figure it the answer out with our hints. Keep the questions coming :)

wee_ws SG

Hi,

By step 1, we obtain

LHS = 2X^2 + 2mx -x - m = 2x^2 + x(2m - 1) - m.

By step 2, we obtain

-m = -3, so m = 3.

By step 3, we obtain

2m - 1 = n, so with m = 3, we have

n = 2(3) - 1 = 5.

Hope these make clear the relationship between our hints and the exact working details.

Here is another question for you to practise:

If (2x - m)(x + 3) = 2x^2 + 5x + n, find the values of m and n.

Jiayou and keep trying!

Cheers,
Wen Shih

16/f/lonely SG

Can one use the Gaussian Elimination method here?

wee_ws SG

Hi,

The method is suited to matrices.

Cheers,
Wen Shih